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Study of crown shapes of Douglas fir, western hemlock, and western red cedar as an aid in the identification… Ronay, Alexander 1961

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i  STUDY OF CROWN SHAPES OF DOUGLAS FIR, WESTERN HEMLOCK, AND WESTERN RED CEDAR AS AN AID IN THE IDENTIFICATION OF THESE SPECIES ON AERIAL PHOTOGRAPHS.  "by ALEXANDER RONAY B.S.F., Sopron D i v i s i o n , U n i v e r s i t y of B r i t i s h . Columbia  1959  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY  i n the Department of FORESTRY  We accept t h i s t h e s i s as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 196l  In the  presenting  requirements  of  3ritish  it  freely  agree for  that  thesis  an  advanced  for  Columbia, available  I  that  copying  gain  shall  by or  not  his  p a r t i a l  degree  fulfilment  at  the  Library  shall  reference  and  study.  I  extensive  may  be  granted  representatives.  allowed  of  this  without  by  of  the  It thesis  Columbia,  make  further this  Head  is  of  thesis my  understood  for  my w r i t t e n  Department The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada.  copying  of  University  the  publication be  in  that  for  purposes  or  agree  for  permission  scholarly  Department  this  f i n a n c i a l  permission.  ii  ABSTRACT  The photo-interpreter has a d i f f i c u l t task when he i s asked t o i d e n t i f y the images of tree species recorded on a e r i a l photographs.  When a  tree i s examined on an a e r i a l photo f o r such a purpose, the d i f f i c u l t y becomes more and more evident as i t i s r e a l i z e d  that the d i f f e r e n t species can not  always he i d e n t i f i e d by eyesight, even on l a r g e - s c a l e photographs, but must be viewed s t e r e o s c o p i c a l l y , and the v a r i a t i o n s i n appearance w i t h i n the same species, even growing under the same c o n d i t i o n s , are very great. In comparison w i t h i d e n t i f i c a t i o n on the ground, the i n t e r p r e t e r must take an e n t i r e l y new approach i n the determination of various species from a e r i a l photographs.  This approach involves t r a i n i n g the eyes to recognize  plants appearing w i t h various hues and grey tones on black and white photographs, at much smaller scale than usual i n ground studies, i n most cases from above or h a l f - o b l i q u e view of the t r e e , which i s strange t o the inexperienced i n t e r p r e t e r . Most of the trees appear on a e r i a l photographs i n v e r t i c a l or oblique views, when the branching habit and the crown shape of a tree are e a s i l y v i s i b l e .  For  t h i s purpose i t i s d e s i r a b l e t o know the c h a r a c t e r i s t i c branching h a b i t and t y p i c a l crown shapes'of trees  i n order t o use these f a c t o r s i n species iden-  tification. This leads up t o the problem that w i l l be presented i n t h i s t h e s i s . Factors which influence the ground c h a r a c t e r i s t i c s of three major tree species i n B r i t i s h Columbia are examined and analyzed. Various crown forms, w i t h which  Douglas f i r , western, hemlock and western red cedar occur i n the v i c i n i t y of Haney and Vancouver are described.  The b a s i c p i c t o r i a l elements^with which  these species appear and enable us to recognize them on a e r i a l photographs, are analyzed. Influence of d i f f e r e n t f i l m s and f i l t e r s on the appearance of species on a i r photos are also discussed.  The t h e s i s presents an a n a l y s i s  of i d e n t i f i c a t i o n s of species made by several i n t e r p r e t e r s . f o r p h o t o - i n t e r p r e t a t i o n are also discussed.  Requirements  F i n a l l y , a dichotomous key i s  presented, which i s constructed f o r Douglas f i r , western hemlock and western red cedar, t a k i n g i n t o account t h e i r appearance at various ages and l o c a t i o n s .  iv CONTENTS Page TITLE PAGE  i  ABSTRACT  i i  CONTENTS  iv  TABLES  vi  ILLUSTRATIONS ACKNOWLEDGEMENTS INTRODUCTION  1  APPROACHES TO IDENTIFICATION OF SPECIES ON AERIAL PHOTOGRAPHS . . .  5  COLLECTION  12  OF FIELD DATA  FIELD CHARACTERISTICS OF A TREE SPECIES THAT FACILITATE ITS IDENTIFICATION  l8  Size  18  Shape  22  The crown shape o f Douglas f i r  25  The crown shape o f western hemlock  26  The crown shape o f western r e d cedar  27  FACTORS INFLUENCING CHARACTERISTICS OF DOUGLAS FIR, WESTERN HEMLOCK AND WESTERN RED CEDAR  29  INFLUENCE OF STOCKING  35 39  INFLUENCE OF AGE Changes i n upper p o r t i o n  o f t h e crown  Changes i n t h e lower p o r t i o n  o f t h e crown  INFLUENCE OF ELEVATION  39 k2 k-2  PHOTO FACTORS WHICH FACILITATE SPECIES IDENTIFICATION  kk  VALUE OF TONE  kk  The importance o f tone t o t h e f o r e s t i n t e r p r e t e r  kk  F a c t o r s c o n t r o l l i n g t h e tone o f an o b j e c t  ^5  V •  CONTENTS (cont'd.) Page Measurement of tone  52  Changes i n tone caused by scale of photos  53  VALUE OF TEXTURE  58  The importance of texture to forest interpreter  58  Factors influencing the texture of an object  59  Texture of individual trees  60  Texture of stands of trees  6k  Measurement of texture  66  VALUE OF FILM AND FILTER  72  FILMS  72 Orthochromatic films  73  Panchromatic films  73  Infra-red films  75  Colour films  79  FILTERS  82  VALUE OF SEASON TO PHOTOGRAPHY  84  Spring and f a l l photography  8h  Summer photography  85  Winter photography  86  EVALUATION OF DIFFERENT PHOTO SCALES IN INTERPRETATION OF TREE SPECIES THE VALUE OF HUMAN FACTORS IN PHOTO-INTERPRETATION  87 93  Visual accuity  93  Mental accuity  95  KEY TO AERIAL IDENTIFICATION OF DOUGLAS FIR  97  CONCLUSION  101  REFERENCES CONSULTED  103  APPENDIX  107  vi  TABLES Number 1  Page Averaged data f o r Douglas f i r , western hemlock, and western red cedar t r e e s , with t h e i r standard d e v i a t i o n s . . .  15  V a r i a t i o n s i n some c h a r a c t e r i s t i c s of Douglas f i r , western hemlock, and western red cedar i n U.B.C. Research Forest a t Haney and i n U.B.C. Campus Forest  16  3  Averaged diameter f o r lowest dead branches  19  k  Average height to the lowest dead and l i v e branches of Douglas f i r , western hemlock, and western red cedar w i t h t h e i r standard deviations  20  5  Average l i v e branch length (FT.) of Douglas f i r , western hemlock, and western red cedar  21  6  Averaged crown width measurements (Ft.) i n Douglas f i r , western hemlock and western red cedar  21  7  Linear m u l t i p l e - r e g r e s s i o n equations f o r dead branch diameter on d.b.h., age, s i t e , index and b a s a l area  29  8  Linear m u l t i p l e - r e g r e s s i o n equations f o r height to dead branches  30  9  Natural pruning of 52 mature Douglas f i r , 58 mature western hemlock and h'J mature western red cedar trees 31  2  10  Linear m u l t i p l e - r e g r e s s i o n equations f o r height t o l i v e branches  11  Regression equations f o r l i v e crown length on d.b.h.,  32  T o t a l height and CW/D  32  12  Regression equations f o r percentage of l i v e crown on b a s a l area per acre and H/CW  33  13  Relationships between Crown Width and d.b.h. of f u l l y opengrown Douglas f i r and western hemlock trees 3^  14  Ratios of Crown Width/d.b.h. by species and stocking  36  15  Comparison of c o r r e l a t i o n s between Crown Width/d.b.h. and height/Crown Width r a t i o s w i t h eleven v a r i a b l e s f o r Douglas f i r , western hemlock and western red cedar  37  16  Relationships among Crown Width, d.b.h., age, t o t a l height, s i t e index and b a s a l area 38  vii TABLES (cont'd) Number 17 18 19 20  Page Regression equations for estimate of Crown Width/d.b.h. from height/CW., or height/CW from C¥/d.b.h., by species.. 38 Average top-angle values with their standard deviations for Douglas fir, western hemlock and western red cedar.... hO Quotient of average top-angle and average crown height for Douglas fir, western hemlock and western red cedar.... hi Distribution of crown shapes of Douglas fir (F), western hemlock (H), and western red cedar (C) hi  21  Changes in reflected light caused by angle of viewing  22  Human ability in separation of different tones  23  Reflected light densities from leaves of some Coniferous and Deciduous species Changes in tone of Douglas fir on different scales of photos Changes in tone of western hemlock on different scales of photos Changes in tone of western red cedar on different scales of photos Changes in texture of Douglas fir on different scales of photographs  2h 25 26 27 28 29 30  Changes in texture of western hemlock on different scales of photographs Changes in texture of western red cedar on different scales of photographs Errors committed in recognition of species by different interpreters on various scales of photos  h6 51 51 56 56 57 70 71 71 91  31  Percentage correctness of photo-interpretation figure for species 92  32  Percentage correctness of photo-interpretation figure for species in different age classes  92  viii  ILLUSTRATIONS To follow Pages Nos. On Page No.  Figure 1 2 3 k Graph 1 2 3  Shape scale Variations in crown shapes of Douglas Fir Variations in crown shapes of western hemlock Variations in crown shapes of western red cedar Average top-angles over age for Douglas fir Average top-angles over age for western hemlock  2k 25 26 28  39 39  Average top-angles over age for western red cedar  39  Figure 5  Tone scale  5  6  Texture scale  68  7  Sensitivity curve of various types of film  APPENDIX I. Photographs showing variations in crown shapes of Douglas fir APPENDIX II. Photographs showing variations in crown shapes of western hemlock ... APPENDIX III Photographs showing variations in crown shapes of western red cedar  2  73  109 113 115  ix  ACKNOWLEDGEMENT  The w r i t e r o f t h i s t h e s i s wishes t o e x p r e s s h i s s i n c e r e thanks t o Dr. J . H. G. Smith, A s s o c i a t e  Professor  o f F a c u l t y o f Forestry at the  U n i v e r s i t y o f B r i t i s h Columbia, f o r h i s u s e f u l s u g g e s t i o n , guidance, and encouragement.  F i n a n c i a l a s s i s t a n c e r e c e i v e d from t h e F a c u l t y o f F o r e s t r y and from t h e U n i v e r s i t y o f B r i t i s h Columbia R e s e a r c h F o r e s t gratefully  acknowledged  Committee i s  by t h e w r i t e r .  Acknowledgement i s a l s o due t o t h e s t a f f members o f t h e U n i v e r s i t y Research Forest  f o r t h e i r assistance  i n collection of f i e l d  data, and t h e U n i v e r s i t y o f B r i t i s h Columbia F a c u l t y o f F o r e s t r y f o r u s i n g t h e i r photographs and equipment.  -1 -  STUDY OF CROWN SHAPES OF DOUGLAS FIR, WESTERN HEMLOCK, WESTERN RED CEDAR AS AN AID IN THE IDENTIFICATION OF THESE SPECIES ON AERIAL PHOTOGRAPHS.  Introduction  Aerial photographs have played an important role in developing Forestry since its first application in 1920 and particularly 19^+0-^5 in the United States and Canada. It is highly valued by Foresters, because it serves as an excellent record of contemporary forest conditions. In fact, aerial photographs are one of the best obtainable forest records, since they can be consulted and supplemented at any time. Foresters have made use of aerial photography in four major fields: a. mapping, b. mensuration, c. reconnaissance and management planning, d. interpretation of forest condition, and vegetation. Forest mapping is concerned with preparing planimetric base maps and detailed topographic maps of a forest property. Map preparation is greatly facilitated by the use of aerial photographs, which leads to greater efficiency and economy of manpower, field surveying time, and cartographic operations.  -  2  -  In f o r e s t mensuration, a e r i a l surveying methods have proved to be l e s s expensive and often more accurate than ground c r u i s i n g .  Stand volume  and conditions can be determined d i r e c t l y or i n d i r e c t l y from a e r i a l photographs.  At the present, i n v e n t o r i e s are most widely accepted.  In the  s t r a t i f i e d and random sampling techniques, p l o t l o c a t i o n s are f i r s t established on contact p r i n t s , and then located i n the f i e l d and cruised by conventional methods.  The volume of the e n t i r e f o r e s t t r a c t i s then  c a l c u l a t e d by expanding the data from these sample p l o t s .  Areas occupied by  the various f o r e s t cover types are determined d i r e c t l y from a e r i a l  photographs  by simple methods (by d o t - g r i d , or l i n e - t r a n s e c t methods, e t c . ) . Reconnaissance and forest-management planning also b e n e f i t from the "bird's-eye view" of an e n t i r e f o r e s t property provided from a e r i a l photography.  Photographs help the f o r e s t e r to i d e n t i f y the p a t t e r n of l o c a l  physiography, to separate f o r e s t cover types and stand c o n d i t i o n s , and to r e v e a l a progress of logging and management operations. The timber c r u i s e r can u t i l i z e a e r i a l photos as one of the most e f f i c i e n t and economical means of l o c a t i n g valuable timber species and stands.  In non-developed  and  i n a c c e s s i b l e f o r e s t t r a c t s , i t i s often the only p r a c t i c a l means.  The  logging engineer can use the same photography i n planning l o g g i n g s e t t i n g s and the roads needed f o r timber e x t r a c t i o n .  The f o r e s t manager and  administrator can f u r t h e r u t i l i z e t h i s photography to d i v i d e the f o r e s t property i n t o compartments consistent with the desired i n t e n s i t y of management. The f i e l d of i n t e r p r e t a t i o n of f o r e s t conditions i s concerned with i d e n t i f i c a t i o n and s p a t i a l d i s t r i b u t i o n of vegetative types p l a n t species.  -3 Forest-cover types are delineated on the b a s i s of d i f f e r e n c e s i n species composition of the dominant tree l a y e r , stand height, d e n s i t y , and s i t e . With adequate f i e l d experience, i t i s possible to i n t e r p r e t  and delineate  cover types even from small scale a e r i a l photos. Much u s e f u l information can be obtained from a e r i a l  photographs  to be applied f o r f o r e s t r y purposes, w i t h s u f f i c i e n t degree of accuracy. Species i d e n t i f i c a t i o n , however, remains as one component, which i s except i o n a l l y d i f f i c u l t to obtain r e l i a b l y i n t h i s way.  This i s due p a r t l y to the  conditions under which the p i c t u r e s were made, l i m i t a t i o n s of photographic equipment and m a t e r i a l s , and the small scale of photographs.  Species  i d e n t i f i c a t i o n i s uncertain on small-scale photographs, but to take l a r g e - s c a l e photographs always involves the question of a v a i l a b l e money.  Large-scale  photographs, covering smaller area than the small-scale photos, are expensive and i n c e r t a i n cases not economical. Tree species are i d e n t i f i e d on a e r i a l photograpias through a process of e l i m i n a t i o n .  The f i r s t step i s to e l i m i n a t e those species  whose  appearance on an area i s impossible or h i g h l y improbable, because of l o c a t i o n , physiography or climate.  The second step i s through a knowledge  of the common a s s o c i a t i o n and of t h e i r e c o l o g i c a l and s i t e requirements, to e s t a b l i s h which group of species occur or may occur i n the area examined. The i d e n t i f i c a t i o n of i n d i v i d u a l tree species i n the group, using crown c h a r a c t e r i s t i c s , u s u a l l y i s the f i n a l stage of t h i s process.  Field  experience and other studies o f the f o r e s t concerned are e s s e n t i a l , but i n t e n s i v e l o c a l knowledge i s a l s o d e s i r a b l e . A e r i a l photographs are becoming more and more important i n  - h -  Forestry, e s p e c i a l l y here i n B r i t i s h Columbia.  As the e x i s t i n g f o r e s t s are  depleted around sawmills, the i n t e r e s t turns to more d i s t a n t v i r g i n f o r e s t . Examination o f such areas by conventional ground-surveying techniques i s very expensive. Taking good f o r e s t inventory i n B r i t i s h Columbia i s very d i f f i c u l t due to i t s rough t e r r a i n , poor a c c e s s i b i l i t y , and weather conditions. R e l i a b l e information about the area examined can be secured cheaply and e f f i c i e n t l y from a e r i a l photographs.  I f we can improve the techniques of  species i d e n t i f i c a t i o n from photos, a e r i a l photographs i n the hands of a f o r e s t manager w i l l become v i r t u a l l y indispensable.  -5 -  APPROACHES TO IDENTIFICATION OF SPECIES ON AERIAL PHOTOS ( REVIEW OF LITERATURE )  In. North America the f i r s t known a p p l i c a t i o n of a e r i a l photogrammetry was by the Union Army i n May, 1862 when captive balloons were used i n photographing the t e r r a i n near Richmond, U.S.A. (Landen,  1952).  Several authors have reported that at the t u r n of the Century s e v e r a l U. S. Forest Service o f f i c i a l s were cognizant of inherent p o s s i b i l i t i e s of a e r i a l photos, but not u n t i l 1919 clid Ralph Thelen put h i s thoughts on paper about usefulness of a e r i a l photos i n f o r e s t r y .  He o u t l i n e d the  experience of the U. S. A i r Force during World War I , and described a general approach f o r a p p l i c a t i o n of a e r i a l photos f o r mapping and resource study.  H i s a r t i c l e brought no immediate r e s u l t s so f a r as p r a c t i c a l  a p p l i c a t i o n by the U. S. Forest Service was concerned. The problem of i n t e r p r e t a t i o n of vegetation was apparent from the beginning of World War I , when photos were used f o r m i l i t a r y purposes. Knowledge of i n t e r p r e t a t i o n at that time involved only the separation of w i l d and c u l t i v a t e d vegetation, grassland from bushy land, shrubs from timber, coniferous f o r e s t from deciduous f o r e s t s and the separation of dense and t h i n stands. f i r s t stage.  Species r e c o g n i t i o n , however, was i n i t s very  Recognition keys were not yet described, and therefore the  a p p l i c a t i o n of species i d e n t i f i c a t i o n was very l i m i t e d .  I n the l a t e  1920's, when oblique and v e r t i c a l photos were applied f o r f o r e s t r y purposes f o r the f i r s t time, the problem of species r e c o g n i t i o n came up i n c r e a s i n g l y . In the e a r l y  1930's, when f o r e s t i n v e n t o r i e s were s t a r t e d i n Alaska, i n the  - 6 -  Rocky Mountain Region, and i n C a l i f o r n i a "by the U. S. Forest Service, not only improved mapping procedures and equipment were developed, but a l s o d e t a i l e d keys and other i n t e r p r e t a t i o n aids were constructed and worked out, based upon the r e l a t i v e s i z e and appearance of vegetation. In 1933  Harrison Ryker published h i s remarkable a r t i c l e about  problems of species determination.  In t h i s study he c a l l e d a t t e n t i o n f o r  the f i r s t time t o the determination of Northwest tree species from a e r i a l photos by use of t h e i r c h a r a c t e r i s t i c crown forms.  The use of a e r i a l  photos, by t h i s time, spread r a p i d l y i n f o r e s t i n v e n t o r i e s , p a r t i c u l a r l y when the U. S. Department of A g r i c u l t u r e began i t s program of photography at an RF of  1 : 20,000.  A r t i c l e s w r i t t e n during the e a r l y  1930's, however,  discussed mainly the importance of tree-height measurements by p a r a l l a x , hence the problem of species r e c o g n i t i o n f e l l i n t o the background.  Most  of the studies were d i r e c t e d on German and other European achievements and the accuracy of photo versus f i e l d measurements.  For about a decade a great  number of papers were issued i n North America about the research of Hugershoff, d e s c r i b i n g t e s t s i n which f o r e s t stands were measured photogrametrically, and how these measurements are r e l a t e d t o a c t u a l volume and other characteristics.  Results of these studies e s t a b l i s h e d the e f f i c i e n c y of p a r a l l a x  measurements of tree height, d i r e c t photographic measurement of crown diameter, and the p o s s i b i l i t y of preparing volume t a b l e s based on these parameters. Although the problem of obtaining r e l i a b l e q u a n t i t a t i v e measurements was thrust i n t o prominence, the question of r e c o g n i t i o n of various species has always been of i n t e r e s t , although progress was l i m i t e d u n t i l  World War I I . The f a c t that the vegetation i s a r e l a t i v e l y r e l i a b l e i n d i c a t o r of ground conditions has been applied often f o r m i l i t a r y operations, and during the e a r l y  19^0's a great emphasis was placed by  armed f o r c e s on photo i n t e r p r e t a t i o n . Many f o r e s t e r s , both i n the U. S. and Canada, were f i r s t introduced t o the r e c o g n i t i o n of various tree and other vegetation species from a e r i a l photos.  During World War I I most of  the key c h a r a c t e r i s t i c s were described, not only f o r r e c o g n i t i o n of i n d i v i d u a l species, but a l s o f o r a s s o c i a t i o n s .  A f t e r the war the f o r e s t e r s  employed by armed f o r c e s , such as H. A. Jensen, R. N. C o l w e l l , and K. E. Moessner, t o mention a few, already s k i l l e d i n i n t e r p r e t a t i o n of the vegetation and other t e r r a i n c o n d i t i o n s , found i n f o r e s t inventories an opportunity t o c a p i t a l i z e on both t h e i r c i v i l and m i l i t a r y And so from 19^6  experience.  on, the l i t e r a t u r e i s f i l l e d w i t h d i s c u s s i o n of the  technique of f o r e s t c l a s s i f i c a t i o n , the problem of i d e n t i f i c a t i o n of tree species, the use of both panchromatic and i n f r a r e d photos i n f o r e s t i n t e r p r e t a t i o n w i t h various s c a l e s , and the many problems of obtaining both q u a l i t a t i v e and q u a n t i t a t i v e measurements. In  19^-6,  C o l w e l l published an a r t i c l e about the i d e n t i f i c a t i o n  of various plant species, and provided a key as an a i d f o r such purposes. Soon i t was followed by Moessner's study  (19^8), which  a l s o dealt w i t h  a e r i a l photographic i n t e r p r e t a t i o n of vegetation f o r f o r e s t i n v e n t o r i e s . Following these, numerous other a r t i c l e s were published about the problem of species r e c o g n i t i o n (Stoeckeler 19^9; Wilson 1953) criptive  and  1952;  Stone 19^8;  and various r e c o g n i t i o n keys were constructed.  Wieslander and Both des-  dichotomous keys were developed f o r study of i n f r a r e d and  panchromatic f i l m s (Schulte  1951;  O'Neill  1953).  -  8  -  Foresters s k i l l e d i n c l a s s i f y i n g f o r e s t types and i n species i d e n t i f i c a t i o n by means of key species i n ground i n v e n t o r i e s , n a t u r a l l y t r i e d t o recognize the same species on a e r i a l photos.  They t r i e d t o r e l y  on the tone of the photo and were confused when d i f f e r e n c e s c l e a r l y v i s i b l e on ground, such as between dark c o n i f e r s and much l i g h t e r hardwood f o l i a g e , were not always d i s t i n g u i s h a b l e on a e r i a l photos.  I t was soon  found that uniform timber stands r e g i s t e r w i t h many d i f f e r e n t tones and that the d i r e c t i o n of l i g h t , the size and density of the f o l i a g e , and the r e s u l t i n g shadows have f a r more e f f e c t than the mere d i f f e r e n c e s i n colour of the species, which appear on the ground.  The l i m i t a t i o n s and uses of  t h i s e f f e c t were achieved by a p p l i c a t i o n of d i f f e r e n t f i l m and f i l t e r s i n combination. A s p e c i a l kind of colour f i l m , c a l l e d camouflage detection f i l m , was developed during World War I I f o r detecting f r e s h l y cut t r e e s or bushes used as camouflaging m a t e r i a l .  The f o l i a g e of cut trees appeared  on t h i s kind of f i l m w i t h a hue e n t i r e l y d i f f e r e n t from that of t h e i r surroundings,  since they were r e f l e c t i n g wave-lengths d i f f e r e n t from  living foliage.  Camouflage-detection f i l m i s a colour f i l m , i n which  three emulsions, coated on a single f i l m base, are s e n s i t i v e t o v i s i b l e green, v i s i b l e red and i n f r a r e d l i g h t s .  The s e n s i t i v i t y of the f i l m i s  such that high i n f r a r e d - r e f l e c t i v e objects, such as healthy green vegetation, r e g i s t e r as v i s i b l e red. Green objects which are not h i g h l y i n f r a r e d r e f l e c t i v e r e g i s t e r as blue, and r e d objects which are not h i g h l y i n f r a r e d r e f l e c t i v e , r e g i s t e r as green.  Since the f i l m i s used i n conjunction with  a Wratten 15 f i l t e r , which absorbs the v i s i b l e blue l i g h t , the blue objects r e g i s t e r as black.  Accordingly, r e d objects which are not h i g h l y i n f r a r e d -  - 9-  r e f l e c t i v e , such as rusted leaves, record as yellow or brown ( C o l w e l l  1956). Immediately a f t e r World War I I , many f o r e s t e r s thought that the problem of species i d e n t i f i c a t i o n could be solved by the use of camouflagedetection f i l m .  Research a f t e r World War I I i n d i c a t e d that the a p p l i c a t i o n  of such f i l m was u s e f u l only f o r studying c e r t a i n kinds of insect damage. (Manual of Photographic  I n t e r p r e t a t i o n , i960.)  The i n f r a r e d , and modified  i n f r a r e d f i l m s which were developed..later, proved t o be much more e f f i c i e n t i n species i d e n t i f i c a t i o n .  Modified i n f r a r e d f i l m s have been used w i t h  various f i l t e r s i n the Northeastern States f o r inventory and i n the Harvard Forest f o r research purposes w i t h photos of RF 1 : 20,000 and 1 : 15,8^0. The p r i n c i p a l c o n t r i b u t o r s on t h i s subject i n recent years have been Jensen and C o l w e l l (19^9), Spurr (1959), Losee (1951), and Schulte (1951). In Canada, s e v e r a l f o r e s t e r s cooperated on studies and d i d some b a s i c work on how f i l m s , f i l t e r s , s c a l e s , and other f a c t o r s a f f e c t photography and the f o r e s t r y values of f i n i s h e d p r i n t s , through a Subcommittee on Forest Surveys of the Canadian Society of Forest Engineers  (Spurr 19^-9) •  At present, many f o r e s t i n t e r p r e t e r s are e n t h u s i a s t i c about the use of colour f i l m , seeing i n colour transparencies a means of recognizing species, provided the f i l m can be reduced i n cost and p r a c t i c a l means can be devised f o r using the transparencies outside the laboratory.  However,  the same v a r i a t i o n s i n tone due t o the d i r e c t i o n of the sun and shadows are present just as much i n colour p r i n t s , as i n panchromatic or i n f r a r e d f i l m s , and may be equal as a source of m i s i n t e r p r e t a t i o n (Waldo 1950)determination of species by t h e i r d i f f e r e n c e s i n r e f l e c t i v i t y does not  The  - 10 n e c e s s a r i l y involve the use of colour f i l m because i t can be made just as w e l l on much cheaper black and white photographs.  Based on Becking's  (1959)  experience, there seems t o be l i t t l e advantage f o r colour f i l m i n summer photography f o r i d e n t i f i c a t i o n of species and f o r e s t types.  However,  r e l a t i v e l y l i t t l e research has been c a r r i e d out i n t h i s d i r e c t i o n t o date. S p e c t r a l a n a l y s i s has been used t o f i n d the r i g h t f i l m - f i l t e r combinations which would r e g i s t e r objects i n a desired tone. Smith  (1957)  undertook a survey f o r t h i s purpose.  Hindley and  Reflectance measurements  were made from leaves of nine of B r i t i s h Columbia's major coniferous species. The measurements showed that the s p e c t r a l a n a l y s i s of tree f o l i a g e would not be p a r t i c u l a r l y h e l p f u l i n choosing the best f i l m - a n d - f i l t e r for  combinations  species i d e n t i f i c a t i o n , because the d i f f e r e n c e s i n r e f l e c t a n c e between  two species were often smaller than the d i f f e r e n c e s between two p l a n t s of the same species. If timber i n v e n t o r i e s are based on f o r e s t stand maps compiled from a e r i a l photographs, i t becomes necessary t o check and v e r i f y the i d e n t i f i c a t i o n of f o r e s t types on the photographs before the type or stand maps are constructed.  F a i l u r e t o make such checks may lead t o serious  e r r o r s i n the determination of stand components i n the area summary, and subsequently  i n the volume and growth estimates.  checking i s c a l l e d c l a s s i f y i n g or coding. e i t h e r the ground or the a i r . From 1951,  The procedure of such  This may be accomplished from when i t was i n i t i a t e d , u n t i l  B. C. Forest Service coding was confined t o ground examination only.  1953, Since  1954 the B. C. Forest Service has done a great d e a l of a e r i a l coding. In 19^9,  Chapman ( l ) published h i s remarkable a r t i c l e about the  - 11 use of h e l i c o p t e r s f o r f o r e s t reconnaissance and mapping.  He o u t l i n e d  the advantages over ground surveys of sketch mapping of f o r e s t s from such machines and concluded w i t h some comments on f l y i n g i n h e l i c o p t e r s . paper was followed by Johnson's  (1952) a r t i c l e  Chapman's  i n which was emphasized the  necessity of checking f o r e s t p h o t o - i n t e r p r e t a t i o n .  Johnson a l s o suggested  that such checking can be done q u i c k l y and e f f i c i e n t l y from l o w - f l y i n g aeroplanes or h e l i c o p t e r s , p a r t i c u l a r l y over large or i n a c c e s s i b l e areas. To obtain good r e s u l t s a new method of i n t e r p r e t a t i o n had t o be developed, which r e t a i n e d some techniques of p h o t o - i n t e r p r e t a t i o n , but d i f f e r e d l a r g e l y from i t . In 1953,  coding from the a i r commenced on an experimental b a s i s  and has c o n s i s t e n t l y proved t o be s u i t a b l e f o r both reconnaissance and inventory standards of mapping.  I n 195^ and 1955  i t was used e x t e n s i v e l y  i n the United States and Canada f o r inventory work, a period during which techniques were modified and improved.  I n 1956  intensive or " s p e c i a l "  coding was commenced i n many parts of North America.  I n B r i t i s h Columbia  ground coding remained as the p r i n c i p a l method of stand c l a s s i f i c a t i o n throughout 195^- n d 1955, a  large  but by 1956  i t was replaced by a i r coding t o a  extent. I t i s expected that i n the future a i r coding w i l l replace ground  coding e n t i r e l y i n inventory work, except f o r surveys which require very intensive c l a s s i f i c a t i o n and f o r the coding- of small areas.  - 12 -  COLLECTION OF FIELD DATA  V e r t i c a l a e r i a l photographs are of i n c a l c u l a b l e value to the f o r e s t manager as a source of information about the area examined. used i n almost every phase of f o r e s t r y work.  They are  The s i n g l e f o r e s t r y a c t i v i t y  i n which a e r i a l photographs are used most i s i n inventory.  The problem of  i d e n t i f y i n g i n d i v i d u a l tree species on a e r i a l photographs, -however, g r e a t l y hinders the wider a p p l i c a t i o n of photos i n f o r e s t inventory.  Since most  trees can be seen on a e r i a l photographs i n v e r t i c a l or oblique views, i t has been found advantageous to l e a r n the c h a r a c t e r i s t i c branching h a b i t and t y p i c a l crown form of tree species and to use mainly these f a c t o r s i n t h e i r identification.  This study w i l l d e a l , therefore, p r i m a r i l y w i t h branching  n a b i t and v a r i a t i o n s i n the crown form of three important B r i t i s h Columbia c o n i f e r s ; Douglas f i r , western hemlock, and western red cedar. The data f o r t h i s study were c o l l e c t e d i n the U.B.C. Campus Forest and i n the U n i v e r s i t y Research Forest a t Haney, during the summer months of i 9 6 0 .  Before d i s c u s s i o n of the data, the Research Forest w i l l be  described b r i e f l y . Location -- The U n i v e r s i t y Research Forest i s located n o r t h of Haney, B.C. I t covers about 10,000 acres, s i t u a t e d w i t h i n the Coastal Mountains of southern B r i t i s h Columbia.  The Forest i s bounded by G a r i b a l d i Park, P i t t  Lake, and the a g r i c u l t u r a l lands of P i t t Meadows. Topography -- The e l e v a t i o n range of the Forest i s from sea l e v e l to  - 13 2,600 f e e t above sea l e v e l .  -  The area contains three p a r a l l e l v a l l e y s each  w i t h a more or l e s s southerly aspect.  In the most e a s t e r l y v a l l e y l i e s  Marion Lake and the west fork of the Worth Alouette R i v e r .  The most  westerly v a l l e y contains Loon Lake, which i s about one mile long and acres i n area.  120  The ridges of t h i s v a l l e y contain numerous rock outcrops  and v a r i a b l e slopes.  The t h i r d v a l l e y slopes to the northeast u n t i l i t  reaches 2,600 f e e t i n e l e v a t i o n .  Then f i n a l l y the southern p o r t i o n of the  Forest has an e n t i r e l y southern exposure w i t h low e l e v a t i o n .  Slopes of t h i s  p o r t i o n of the area have numerous rock outcrops and b l u f f s and vary g r e a t l y i n steepness (U.B.C. Forest Committee, 1959)S o i l -- The s o i l of the Research Forest i s mainly of g l a c i a l - t i l l o r i g i n . I t i s exceedingly rocky and of a sandy-loam t e x t u r e , v a r y i n g i n depth from a few incnes to three or more f e e t ( G r i f f i t h , i 9 6 0 ) . Forest Types -- There are four main f o r e s t types i n the Research Forest: ( l ) Old growth, (2) Scattered old growth, (3) Second growth, and  (k)  Reproduction. (1)  Old growth -- About 80$> of the east slope of north c e n t r a l  ridge i s covered by t h i s type of stand.  The stands c o n s i s t of over-  mature cedar-hemlock-fir, w i t h scattered white pine and balsam. (2)  Scattered o l d growth -- This type i s found predominantly i n the  western p o r t i o n of the Forest. Douglas f i r i s the major species i n these scattered stands and occurs i n groups or as s i n g l e t r e e s . (3)  Second growth -- About 20$ of the e n t i r e Forest i s covered w i t h  second-growth  stands, which are about e i g h t y years o l d . The major  species i n the second-growth  are hemlock and cedar.  can be found i n small patches w i t h i n these stands.  A few s i l v e r f i r s  - 14 (4)  Reproduction -- Reproduction occupies about 45$ of the productive  area of the Forest.  The logged areas i n the d i f f e r e n t parts of the  Forest have various stages of reproduction. Douglas f i r i s uniformly but sparsely d i s t r i b u t e d through the area, together w i t h many hemlock and cedar t r e e s .  Scattered white pines and small patches of alder  occur i n the Forest. Most of the measured trees were chosen from the second growth of the Forest, s i t u a t e d i n the western v a l l e y at e l e v a t i o n s from 700 to f e e t , w i t h ages of 70 to bO years.  1,200  Older Douglas f i r t r e e s , w i t h ages of  about 130 to 150 years, were also measured there.  Old western hemlock and  western red cedar trees were measured i n the northern p a r t of the area at Gwendoline Lake, at approximately 1,900  to 2,200 f e e t e l e v a t i o n .  Procedure -- During the survey, 57 young and 52 o l d Douglas f i r , 58 young and 58 o l d western hemlock, and 55 young and 47 o l d western red cedar trees were measured.  Each tree was randomly chosen on the ground from the group of trees  e a s i l y v i s i b l e on each of the photos to be studied. Each tree was marked on each photograph.  Measurements were taken of the d.b.h., t o t a l height, and  crown width of each tree.  Every chosen tree's crown shape was drawn i n  p r o f i l e and c r o s s - s e c t i o n views, and l a t e r was compared w i t h i t s appearance on each kind of photograph. presented i n Table  The averages of the c o l l e c t e d data are  1.  In a d d i t i o n to these t r e e s , 184 Douglas f i r , l66 western hemlock and 77 western red cedar trees were studied. These represented various environmental conditions and covered a wide range of age classes, i n order to obtain more knowledge about the n a t u r a l pruning a b i l i t y and thereby more about  - 15 Table 1.  Averaged data f o r Douglas f i r , western hemlock, and western red • cedar t r e e s , w i t h t h e i r standard deviations  D.b.h. ( i n . ) Height ( f t . ) Crown width ( f t . )  Douglas f i r  Western hemlock  Western red cedar  Average S.D.  Average S.D.  Average S.D.  h2.b  28.7  ik.Q  8.7  162.7 37.3  126.8 19.7  27.1 28.5  22.8 15.1  37.7 14.9 131.8 23-6 2k.6  the size of the crown components and shapes of these species. and evaluated data on these trees are presented i n Table 2.  lk.8  The c o l l e c t e d  The author  a s s i s t e d i n the c o l l e c t i o n and i n some of the a n a l y s i s of these data which have been used by Smith, Ker and Csizmazia  (1961).  Crown class i n Table 2 means that tree crowns were classed as 10 f o r dominant, 20 f o r codominant and 30 f o r intermediate. Distance t o competitors represents the average values f o r nearest competing trees i n each of W, S, E, and W quadrants, i n r e l a t i o n to the tree being studied. Dead and l i v e branch length and diameters represent d.o.b. and t o t a l - l e n g t h estimates, averaged from values f o r each of W, S, E, and W quadrants. heights were measured w i t h a Haga h e i g h t - f i n d e r .  Total  T o t a l ages were based upon  borings a t breast height w i t h c o r r e c t i o n s f o r years to reach breast height. S i t e index was determined f o r each tree using t a b l e s f o r s i t e index constructed by Meyer and Bruce  (19^9)  f o r Douglas f i r and hemlock tables by  Barnes f o r both western hemlock and western red cedar (Forestry Handbook f o r B r i t i s h Columbia, pp.  369-371)-  Average crown width was determined by  the v e r t i c a l p r o j e c t i o n of the crown measured i n two opposite d i r e c t i o n s . The height of average maximum crown width was recorded.  Basal area per acre  Table 2.  Variations i n some c h a r a c t e r i s t i c s of Douglas f i r , western hemlock and western red cedar i n U.B.C. Research Forest at Haney and i n U.B.C. Campus Forest  s Items  Douglas f i r Avg. SD. Min Max.  p  E C I E S Western hemlock Western red cedar Avg. SD. Min . Max. Avg. SD. Min. Max.  4.6 10.0 20.0 16.1  5.2 10.0 30.0  D.b.h. (In.)  11.7 4.1 10.0 30.0 12.9 19.0 9.6 6.0 50.0 16.4  6.6 5.0 35-0 15.7  7-2 2.6 36.0  D i s t . to comp. (Ft.)  15.6 9.9 0  6.4 4.0 43.0 15.3  7-2 5-0 34.0  Crown class  38.0 15.5  Dead br. length (Ft.)  1.8 1.4 0.5  a.8  1.8  Dead br. diam.  0.58 0.35 0.1  2.3  0.62  (in.)  Live br. length (Ft.)  9-4 3-7 1.5 22.0  Live br. diam. (In.)  1.3 0.6 0.3  Total height (Ft.) Total age (Yrs.) Site index (@ 100)  8.0 2.3 1-7 0.5 •37 0.2 1-9 •55 0,62 0.1  1.3 0.5  8.7 3.4 3.5  3-3 1.1  18.  8.5  1-3  5 6-5 2.9 1.3 14.3  .55 0.4 2.5  • «3 0.34 0.3 1.8 110.0 44.0 29.0236.0 98.0 35.0 35.0162.0 82.0 32.0 25.0128.0 59-7 28.5 20.0151.0 65.O 28.0 23.0125.0 57.8 29.8 22.0188.0 152.0 37-0 60.0 260.0 130.0 25.0  00.0  180.0 116.0 20.0 80.0 165.0  Avg. crown height (Ft.)  6.7 7.0 42.0 17.9 0.5 10.0 38.0 71.5 38.7 6.0 190.0 59-0 29.4 3.0 108.0 46.4 27.4 4.0 95-0  Basal area (Sq.Ft./ac.)  157.0 63.0 20.0 20.0 370.0 164.0 59.0 80.0 290.0 164.0 55.0 30.0  Avg. crown width (Ft.)  Avg. Height to dead br. (Ft.) Avg. Height to l i v e br. (Ft.)  21.5 7-3 8.0 4o.o 18.9  14.8 17.3 1.0 84.0 17.9 19.6 1.0 93-0 9-1 8.1 1.0 30.0 54.5 30.5 2.0 145.0 44.8 25.0 2.0 88.0 29.7 19.6 2.0 75-0  - IT was d e t e r m i n e d f r o m a p r i s m count o f t r e e s s u r r o u n d i n g and i n c l u d i n g t h e studied tree.  Average n e i g h t o f dead branches r e p r e s e n t s averaged h e i g h t  measurements t o t h e l o w e s t dead b r a n c h i n each o f N, S, E, and W q u a d r a n t s . Average h e i g h t t o l i v e branches was d e t e r m i n e d  similarly.  E v e r y chosen t r e e has been marked w i t h a p i n p o i n t on e a c h photograph.  (a)  There were f i v e d i f f e r e n t k i n d s o f photos a v a i l a b l e :  Photographs made i n A p r i l 195^  w i t h a 20-inch f o c a l - l e n g t h  camera on p a n c h r o m a t i c f i l m and p r i n t e d with, a s c a l e o f 330 f e e t / i n c h o r about RF (Jo)  1 : 4,000.  Photographs made i n A p r i l 1954,  w i t h a 20-inch f o c a l - l e n g t h  camera w i t h t h e same f i l m and f i n i s h i n g of (c)  720 f e e t / i n c h  o r about RF  as i n ( a ) above, w i t h a s c a l e  1 : 8,700.  Photographs made i n May 1958,  w i t h a 6-inch f o c a l - l e n g t h  camera on p a n c h r o m a t i c f i l m and p r i n t e d on G e v a e r t paper w i t h g l o s s y f i n i s h , w i t h a s c a l e o f 1,200 (d)  f e e t / i n c h , o r about RF 1 : 14,400.  Photographs made i n June 1959,  with a b-inch f o c a l - l e n g t h  camera on t h e same f i l m and paper as i n ( c ) above, w i t h a s c a l e o f  1,500 (e)  f e e t / i n c h o r about RF  1 : 16,000.  And f i n a l l y , photos made i n May 1958,  w i t h a 6-inch f o c a l - l e n g t h  camera, on t h e same f i l m and f i n i s h as i n ( c ) above and w i t h a s c a l e o f  2,400  f e e t / i n c h o r abour RF  1 : 28,000.  The c o l l e c t e d d a t a were e v a l u a t e d w i t h t h e Alwac I I I . E. computer a t t h e U n i v e r s i t y o f B r i t i s h Columbia.  - 18 FIELD CHARACTERISTICS OF A TREE SPECIES THAT FACILITATE ITS IDENTIFICATION (1) Size Size is a relative impression which relates the surface or volume dimension of an object to the surface or volume dimensions of another known object. It is therefore called Relative Size. If the size of a tree is associated with its shape, it may be a very valuable factor in forest photointerpretation, because it not only helps us to identify the object, but also it can tell something more about it.  In our case, with the help of  size and shape we can separate not only merchantable timber from immature stands, but we may also determine some of the tree species in the examined stand. It has been observed for a long time that the size of Douglas fir trees, in most cases, is greater than than of western hemlock or western red cedar, provided that all the three species are of the same age. In Table 2 it can be seen that the averaged diameter at breast height for Douglas fir has been found to be 19-0 inches with a standard deviation of 9-6 inches; for western hemlock, 1.6.k inches with standard deviation of 6.6 inches; whereas for western red cedar, average d.b.h. is 15-7 inches with standard deviation of "J.2 inches. The differences in size may be pointed out also in the diameter and length of branches for these three tree species. On 36 Douglas fir, grown at average spacing in the University Research Forest at Haney, the diameter of  - 19 branches  i n the first  inches  average  inches  f o r 15  whorl  branch  d i a m e t e r was  western  r e d cedar  Differences branches  of these  f o u n d t o b e 1.31 cedar.  above b r e a s t h e i g h t averaged found  Average  inches f o r Douglas diameter  inches;  hemlock t r e e s ,  O.58  and  0.57  and  dead  trees.  showed up i n d i a m e t e r  species.  The average  f o r 33  0.62  of the lowest  diameters f i r , 1.12  f o rlive  live  branches  f o r hemlock,  f o r dead branches  have  a n d O.83  been  f o rr e d  i s presented i n Table  3  below.  Table  3-  Averaged  diameter Av.  Species  each  0.62 "  0.37 "  W.  r e d cedar  0.55 "  0.62 "  tree.  photos.  differences  species. dead  The a v e r a g e  t h e sake  c a n be used  in  may b e d i f f e r e n c e s of live  Average  The measure and l i v e  they  measured  i n .  i n natural  o f pruning has been  branches  cannot  i t e m s may  which  percentage  are pointed out also  of species recognition  value because  The f o l l o w i n g  i n .  i n four  s u p p l y much more  indirectly  i n separation  k.  crown on a  height found  just  o r d i s c e r n e d on information of species.  i n h e i g h t , crown w i d t h , l e n g t h  as  quadrants f o r  the differences  be measured  pruning of  established  data obtained are presented i n Table  species size  0.53  hemlock  t o the lowest  l i t t l e  SD  W.  For have  Diam.  O.58  three tree  height  branches  Douglas f i r  Significant these  f o r lowest dead  discussed aerial  about  the  Differences  o f crown and  tree.  f o r Douglas  f i r w a s 110  feet  with  SD  of  kk  - 20 Table 4.  Average height to the lowest dead and live branches of Douglas f i r , western hemlock, and western red cedar, with their standard deviations Live branches  Dead branches Avg. Ht.  Avg. Ht.  SD.  SD.  Ft.  Ft. D. f i r  14.8  17.3  5^-5  30.5  w. hemlock  17-9  19.6  44.8  25.0  ¥. r. cedar  9-1  8.1  29.7  19.6  feet.  Minimum height among 184 Douglas f i r trees was found to be 29 and  maximum 236 feet whereas, for 167 western hemlock trees, the average height was 98 feet with SD 35 feet. were 23 and 125 feet.  Minimum and maximum measurements in height  Average height for western red cedar was found to be  82 feet, with SD 32 feet and minimum and maximum measurements of 25 and 128 feet. Crown width may play a great role in separation of tree species. Since the crown width i s determined by the length of live branches in two opposite directions, i t i s worthwhile to examine the length of live branches in order to obtain more knowledge about crown width.  In Table 5 the  average live branch lengths are given for 184 Douglas f i r , 167 western hemlock and 77 western red cedar. Averaged crown width measurements for Douglas f i r , western hemlock and western red cedar are given in Table 6.  According to these figures the  widest crown width measurement has been found for Douglas f i r , which may be explained by the genetic and ecological nature of this species.  - 21 -  Table 5-  Average l i v e branch length (Ft.) of Douglas f i r , western hemlock, and western r e d cedar. Ave. length.  Species  Stand  Dev.  Minimum Maximum measurement s  Douglas f i r  9^  3 7  1-5  22.0  W. hemlock  8.7  3 h  3-5  18.5  ¥. r . cedar  6.5  2 9  1-3  14.3  Table 6.  Averaged crown width measurements (Ft.) i n Douglas f i r , western hemlock, and western r e d cedar.  Species  Ave. width  Stand, dev.  Maximum Minimum measurements  Douglas f i r  21.5  7-3  8.0  4-0.0  W. hemlock  18.9  6.7  7-0  42.0  W. r . cedar  17.9  6.5  10.0  38.0  On the t r e e s studied f o r n a t u r a l pruning the average length of crown f o r Douglas f i r has been found t o be 55 feet w i t h SD 23 f e e t , and feet f o r western hemlock w i t h SD 20 f e e t , and f i n a l l y 52 feet f o r western red cedar with SD 25 f e e t . Percentage t r e e crown on the same t r e e s a l s o has been averaged. They were found t o be 53$ w i t h SD l 8 $ i n Douglas f i r , 58$ w i t h SD 19$ i n western hemlock, and 65$ w i t h SD 20$ i n western r e d cedar. The a p p l i c a t i o n of the s i z e of trees i n determination of t h e i r species i s a very weak clue. to be i d e n t i f i e d .  I t can give us j u s t a guess about the species  I t does not have any importance alone, but using i t i n  combination with other r e c o g n i t i o n f a c t o r s i t may become very u s e f u l .  - 22 -  When a p p l y i n g s i z e i n i n t e r p r e t a t i o n , knowledge  of the scale of  t h e photographs i s e s s e n t i a l , because t h e s c a l e i n d i c a t e s t h e r e a l s i z e o f an o b j e c t .  There a r e some s p e c i a l cases when approximate s i z e s can be  o b t a i n e d w i t h o u t s c a l e , i f o b j e c t s w i t h a known d i m e n s i o n a r e r e c o g n i z e d on p h o t o g r a p h s . by comparison.  F a m i l i a r o b j e c t s can h e l p us t o s e t t h e s c a l e o f a p i c t u r e Where o p p o r t u n i t y  o f comparison and s c a l e a r e m i s s i n g ,  size  l o s e s much o f i t s i m p o r t a n c e . (2)  Shape Shape i s t h e g e n e r a l form and o u t l i n e o r c o n f i g u r a t i o n o f an  o b j e c t , w h i c h i s seen I n two dimensions on s i n g l e p h o t o g r a p h s .  In paired  photographs i t appears i n t h r e e dimensions when v i e w e d s t e r e o s c o p i c a l l y , g r e a t l y f a c i l i t a t i n g t h e i d e n t i f i c a t i o n o f t h e d e s i r e d o b j e c t , by f a c t o r s such as h e i g h t , topography, l e s s e r v e g e t a t i o n , r i v e r s , and c u l t u r a l  f o r e s t stands,  roads, l a k e s ,  features.  On v e r t i c a l a i r p h o t o g r a p h s , t r e e s a r e seen i n an u n u s u a l perspective,  so t h a t many k e y c h a r a c t e r i s t i c s , by w h i c h t r e e s  ordinarily  are i d e n t i f i e d , a r e no l o n g e r v i s i b l e , and s e v e r a l new ones appear.  For  i n s t a n c e , t h e t r u n k o f a t r e e may be h i d d e n by t h e crown, but t h e b r a n c h i n g h a b i t i n t h e upper p a r t o f t h e crown may show i t s e l f  distinctly.  I n g e n e r a l i t i s e a s i e r t o i d e n t i f y t r e e s i n s i d e v i e w , s i n c e more p a r t s o f t h e crown o f t h e examined t r e e can be seen. s p e c i e s can be b e t t e r r e c o g n i z e d  For t h i s reason, tree  on o b l i q u e s , t h a n on v e r t i c a l p h o t o g r a p h s .  T h i s f a c t , however, does not e x c l u d e t h e use o f v e r t i c a l  aerial  photographs i n t h e i n t e r p r e t a t i o n o f t r e e s p e c i e s by t h e i r crown  shapes,  because t r e e s n e a r t h e edges on v e r t i c a l photos a r e u s u a l l y s u f f i c i e n t l y  - 23 displaced t o be seen from the side. The best advantage of v e r t i c a l a e r i a l photographs i s that t r e e s can be viewed s t e r e o s c o p i c a l l y , whereas i n oblique photographs t h i s i s more d i f f icult.  Without a stereoscopic view i t often i s d i f f i c u l t t o recognize even  the most general shape of an object. The growth-form of t r e e s , which i s characterized by t a l l , woody, erect stems, may be separated i n several classes that are u s e f u l f o r recogn i t i o n of t r e e species.  Several such s c i e n t i f i c s h a p e - c l a s s i f i c a t i o n terms  have been developed, but these terminologies d i d not spread widely i n p r a c t i c a l application.  They are e i t h e r d i f f i c u l t t o s p e l l , pronounce and understand,  when compared with corresponding terms, or are r a r e l y a p p l i c a b l e i n the f i e l d of f o r e s t i n t e r p r e t a t i o n (e.g. hippo-crateriform, meaning "horse-shoe shaped"; fundibuliform, meaning "funnel-shaped"; pandurate, meaning etc.,  j u s t t o mention a few).  "fiddle-shaped";  A shape scale f o r f o r e s t p h o t o - i n t e r p r e t a t i o n  should f u l f i l the f o l l o w i n g requirements: a.  I t should be e a s i l y s p e l l e d , pronounced, understood  and therefore u s e f u l i n many t e c h n i c a l keys as w e l l as i n non-technical ones, b.  I t should be precise i n i t s meaning and mathematically  defined, c.  The terms should be applicable t o a great many objects  which the f o r e s t photo-interpreter wishes t o describe. The only suggestion  f u l f i l l i n g these requirements that has come t o  the w r i t e r ' s a t t e n t i o n i s that of C o l w e l l (1952).  C o l w e l l suggested use of  the shape scale already defined i n dendrology f o r d e s c r i b i n g the shapes of leaves.  To apply t h i s suggestion the terms were taken from Harlow and Harrar  (l9^l) .  Ten such terms were used as shape scales i n examination of crown  - 2k  -  shapes of Douglas f i r , western hemlock and western red cedar.  They are  represented i n Figure 1 and defined as f o l l o w s . 1.  L i n e a r - more than four times as long as wide, with n e a r l y parallel  2.  Oblong - about three times as long as wide, with nearly parallel  3-  sides,  sides,  Lanceolate - about four times as long as wide, and broadest below or about the middle; lance-shaped,  k.  Oblanceolate - i n v e r s e l y lanceolate, i . e . about four times as long as wide, and broadest near the apex,  5.  Ovate -  having an o u t l i n e l i k e the l o n g i t u d i n a l section of a hen's egg, and broadest near the base,  6.  Obovate - i n v e r s e l y ovate, i . e . having an o u t l i n e l i k e the l o n g i t u d i n a l section of a hen's egg, and broadest near the apex,*  7.  E l l i p t i c a l - about two times as long as wide, and having an o u t l i n e l i k e an e l l i p s e ,  8.  D e l t o i d - wide at the base, pointed at the top.  Shaped  l i k e the Greek l e t t e r d e l t a ; t r i a n g u l a r , 9.  Rhomboid - s i m i l a r to rhombus, with equal sides but unequal angles.  In other words, i t can be c a l l e d diamond-  shaped, 10.  I r r e g u l a r - no corresponding shape. These above-defined shapes were found to be quite representative  of various crown shapes of d i f f e r e n t tree species which occur e i t h e r i n the open or i n dense stands. * "Ob" i s a L a t i n p r e f i x s i g n i f y i n g i n v e r s i o n . ** Added to Harlow and Harrar's l i s t ; "lobed" might be b e t t e r .  To f o l l o w page 2k  Fig- I  Shape  scale  To follow page 25  - 25 In many cases there are s e v e r a l t y p i c a l crown shapes f o r each species even at the same age and growing under the same conditions.  There w i l l be many  deviations from t y p i c a l crown forms, because shape of the crown v a r i e s g r e a t l y due t o the influence of environment.  Some species are l e s s v a r i a b l e than others,  but i n no case can r u l e s regarding crown shapes be set up, from which exceptions do not e x i s t .  Some species, at a c e r t a i n age, have t y p i c a l crowns, which can  be e a s i l y described by d e f i n i t e terms, such as c o n i c a l , oblong and d e l t o i d . Often, when trees approach t h e i r maturity, d e s c r i p t i o n of shapes i s more d i f f icult.  Because of many i r r e g u l a r i t i e s i n mature crowns, they u s u a l l y can be  described simply as i r r e g u l a r i n shape. The Crown Shape of Douglas F i r The most conspicuous c h a r a c t e r i s t i c of mature Douglas f i r t r e e s i s their gigantic size.  Douglas f i r i s u s u a l l y the t a l l e s t i n d i v i d u a l i n a mixed  stand and the one with the broadest crown. Douglas f i r crowns are u s u a l l y t h i c k , t h i c k e r than those of western hemlock, and have an erected p e n c i l - l i k e top.  The lower branches are s t r a i g h t ,  but the middle and the upper ones tend upward, making the margin of the crown serrulate.  Most of the branches have numerous long-hanging side branchlets.  In younger ages, i f the Douglas f i r grows w i t h i n open stands, the whole trunk i s covered w i t h branches, appearing w i t h broadly pyramidal or d e l t o i d form (Fig. 2a Appendix I . a ) . By the time the surrounding t r e e s form a dense stand, the  trunk becomes f a i r l y c l e a r , w i t h a t y p i c a l ovate crown shape ( F i g . 2d  Appendix I . c ) .  Young t r e e s growing i n f a i r l y dense stands u s u a l l y have narrower  crowns w i t h much longer t i p s , than those growing i n more open stands. As the tree reaches the age of 60 t o 70 years, the v a r i a t i o n s i n crown shape are the  Fig  2  V a r i a t i o n s in C r o w n  Shapes  of  Douglas  fir  Fig- 2 cont'd  V a r i a t i o n s in C r o w n  Shapes  of  Douglas  fir  Fig- 2 cont'd  V a r i a t i o n s in C r o w n  Shapes  of  Douglas  fir  - 26 greatest.  The crown form of Douglas f i r v a r i e s i n t h i s age from a narrowly  pointed t i p t o a very t h i c k top, due t o i t s p a r t i c u l a r inherent, environment, or l o c a l i t y f a c t o r s (Fig.2.f.h. Appendix I . f . j . h . ) . As the Douglas f i r t r e e s approach maturity, the i r r e g u l a r form of the  crown becomes more and more evident.  The i r r e g u l a r i t y of the crown appears  i n enlargement of the branches and the distances between s u r v i v i n g whorls. With diminishing of the v i t a l processes i n the t r e e , some crown components become needless. Some of the branches and whorls accomplishing t h e i r functions i n the l i f e of the t r e e d i e , making by t h i s process large gaps between the rema i n i n g l i v i n g branches and whorls ( F i g . 2 . i . j . ) .  The top of such immature  Douglas f i r s may appear e i t h e r f l a t t e n e d , or with dead tops, forming a "brooml i k e " t i p ( F i g . 2 . k . l . Appendix I.o.p.). The Crown Shape of Western Hemlock Western hemlocks are t a l l t r e e s , w i t h crown length approximately one-third of t o t a l t r e e height.  The shape of immature western hemlock t r e e s  i s t y p i c a l l y c o n i c a l with a narrow top.  I t i s always narrower than that of  Douglas f i r or western red cedar trees i n the same age group.  The top twig  droops g r a c e f u l l y , which i s the most important d i s t i n g u i s h i n g mark f o r separa t i o n of hemlock trees from other major species. and i r r e g u l a r l y spaced on the trunk.  The branches are long, slender,  In most of the cases the end of the  branches i s p o i n t i n g downward, i n contrast to Douglas f i r , w i t h ends of i t s branches u s u a l l y tending upward (Appendix I I . a .  & II.d.).  With increase of  age, the long, narrow crown top becomes shorter, thereby the crown shape changes to a t y p i c a l pyramidal form, from c o n i c a l (Fig.3-b.d.).  As the t r e e reaches i t s  mature age the top becomes more shortened and the upper p o r t i o n of the crown w i l l t u r n  To f o l l o w page 26  Fig-  3  V a r i a t i o n s in C r o w n  c  Shapes  of  Western  hemlock  d  Fig- 3 cont'd  Variations  in C r o w n  Shapes  of  Western  hemlock  - 27 i n t o a d e f i n i t e dome-shaped form ( F i g . 3-e.f • ) , i n which l i v e whorls are located w i t h large gaps and spaces between branches ( F i g . 3«g.h.). In most cases, the crown shapes of immature hemlock trees growing w i t h i n dense stands cannot be a t t r i b u t e d t o a t y p i c a l and d e f i n i t e form as e a s i l y as those of Douglas f i r , or western red cedar. Generally the dark-green f o l i a g e of hemlock trees i s t h i c k , but the crown i s thinner i n appearance than that of Douglas f i r , despite the f a c t that the l a t t e r requires more l i g h t than the former. The Crown Shape of Western Red Cedar The most prominent c h a r a c t e r i s t i c of western red cedar trees i s t h e i r c o n i c a l crown form.  I t can be seen most d i s t i n c t l y , p a r t i c u l a r l y i n  young t r e e s , which are s t r a i g h t , appearing w i t h t y p i c a l c o n i c a l crowns reaching almost t o the ground i f growing i n the open, and tapering t o a sharp top ( F i g . k.a. Appendix I l l . b . ) . curve.  The slender leader may often nod i n a g r a c e f u l  In open growth, cedar trees r e t a i n a l l t h e i r branches u n t i l they reach  25 - 30 years, and may become much older without l o s i n g t h e i r lowest branches (Appendix I I . c ) .  On young trees the slender limbs a l l curve upward, but later  they become very long.  1  With increase of age the end of branches d e f i n i t e l y  point downward. As the tree approaches i t s maturity the crown shape may remain s t i l l pointed, but i t often changes t o a round-shaped form ( F i g . k.d.e.). can be described as a short, b l u n t , or round-topped c o n i c a l head.  It  I t has been  observed i n the Research Forest at Haney that round-shaped mature cedar trees occurred  more often i n denser than i n open stands ( F i g . k.f.).  However, over-  mature cedar trees often tend t o develop a long, narrow top and may have a dead or spike top, by which they can be d i s t i n g u i s h e d even at a long distance  - 28 from other species ( F i g . k.h.  Appendix I l l . f . ) .  Long, i r r e g u l a r branches  of over-mature t r e e s , p a r t i c u l a r l y at the lower p o r t i o n of the crown, downward, and others, i n the upper p o r t i o n of the crown, may tend s l i g h t l y upward. Branches of over-mature cedar t r e e s droop much more than that of Douglas f i r , or western hemlock. A notable feature of o l d red cedar trees i s the frequent occurrence of two or more top leaders, which cause a dense crown, or may form an i r r e g u l a r crown shape o u t l i n e .  I n the Research Forest at Haney, most of the mature cedar  trees that appeared w i t h rounded shape had more than one top leader. Crown density of cedar t r e e s i s about the same as that of hemlock, although there may occur wide v a r i a t i o n s i n crown d e n s i t i e s , even w i t h i n trees of the same age.  This may be explained by d i f f e r e n c e s i n stocking, s i t e  and environment, as w e l l as inherent conditions.  index,  To f o l l o w page 28  Fig- 4  Variations in Crown Shapes of Western red cedar  Fig- 4 cont'd Variations in Crown Shapes of Western red cedar  - 29 -  FACTORS INFLUENCING CHARACTERISTICS OF DOUGLAS FIR WESTERN HEMLOCK AND WESTERN RED CEDAR TREES  The components of a tree crown change with tree age.  Changes  appear mainly i n enlarging of s i z e s and i n r e c o n s t r u c t i o n o f the crown shapes of the t r e e .  There are many f a c t o r s which influence the changes i n crown  components of a t r e e , such as age, s i t e index, b a s a l area, stocking, e t c . Linear m u l t i p l e - r e g r e s s i o n equations were used i n examination of e f f e c t s of these f a c t o r s . The f i r s t step involved the examination of dead-branch diameter .in regression with d.b.h., s i t e index, and b a s a l area.  Dead-branch  diameters i n Douglas f i r and western hemlock were s t r o n g l y associated with d.b.h. and age of the t r e e .  I n the case of western red cedar i t was almost  impossible to c o r r e l a t e the diameter of dead branches with any v a r i a b l e . The l i n e a r m u l t i p l e - r e g r e s s i o n equations are presented i n Table 7 below. Table 7«  Linear m u l t i p l e - r e g r e s s i o n equations f o r dead-branch diameter on d.b.h., age, s i t e index and b a s a l area Intercept  Species  Regression c o e f f i c i e n t s f o r deadbranch diameter on: d.b.h. Age SI Basal area  SE  E  R2  In.  Douglas f i r  0.35  0.0156  .00439  -.00099  .00113  • 27  39-7  W. hemlock  -0.15  0.0150  .OO765  .00005  .00011  .23  62.4  W.r. cedar  0.20  0.0129  .00074  -.00109  .00140  .60  6.0  The amount of pruning, however, i . e . the height t o the dead branches i s influenced by more f a c t o r s .  I n Douglas f i r , western hemlock  - 30 and western red cedar the height of the dead branches increased with the height, age, s i t e index, crown width and height to l i v e branches.  The  height to the dead branches o f hemlock and cedar species decreased w i t h d.b.h. and b a s a l area, whereas i n Douglas f i r i t decreased w i t h d.b.h., but increased with b a s a l area, i n contrast to that o f hemlock and cedar.  I n each o f these  three species, however, age was the most important s i n g l e f a c t o r c o n t r o l l i n g t h e i r n a t u r a l pruning.  The m u l t i p l e - r e g r e s s i o n equations o f height t o dead  branches on d.b.h., age, and t o t a l height were s t a t i s t i c a l l y s i g n i f i c a n t . These equations are presented i n Table 8. Table 8.  L i n e a r m u l t i p l e - r e g r e s s i o n equations f o r height t o dead branches  Species  Intercept  Regression c o e f f i c i e n t s f o r height to the dead branches (Y) on: d.b.h. Age T o t a l Ht.  SE  Douglas f i r  -15.7  -0.215  0.036  0.515  9.6  W. hemlock  -15-3 -4.8  -1.372  0.287  0.423  -0.642  0.179  O.163  13.3 4.9  W.r.  cedar  R  E  2  85.I  53-7 63.3  Examination of the data summarized i n Table 9 shows t h a t old-growth Douglas f i r s are much b e t t e r pruned than western hemlock or western red cedar at Haney.  Differences i n n a t u r a l pruning of old-growth Douglas f i r , u n l i k e  hemlock and cedar, were mainly associated w i t h d.b.h. and height. The v a r i a t i o n i n heights t o the lowest l i v e branches of young trees (Table 2) depends on the d i f f e r e n c e s i n d.b.h., t o t a l height of a t r e e , age and b a s a l area per acre. height t o l i v e branches  The l i n e a r m u l t i p l e - r e g r e s s i o n equations f o r  (presented i n Table 10), show that i n a l l three species  the d.b.h. was the most important f a c t o r which influenced the height t o the  - 31 Table 9.  -  Natural pruning of 52 mature Douglas f i r , 58 mature western hemlock and 47 mature western red cedar trees  Statistics  Species D.b.h.  Means  Standard Deviationis  V a T.Ht.  r i a b Avg.Ht. Crown of lowest Width live branches (Ft.) (Ft.)  1  e s Ht. to Avg.Crown width (Ft.)  Avg.Ht. of lowest live branches (Ft.)  27.1  l4o.7  71.4  55.8  22.8  109.2  42.5  131.9  45.0  24.6  111.4  28.7  14.8  37-3  27.4  7.8  32.4  28.6  H  8.7  19.8  14.9  4.6  19.1  15-1  C  15.0  23.7  19.9  6.7  24.5  14.8  (In.)  (Ft.)  F  42.6  162.7  84.2  H  28.7  126.8  C  37-^  F  C o r r e l a t i o n coef-  F  0.52  0.77  0.89  0.33  0.79  1.00  f i c i e n t s w i t h Av.  H  0.29  o.4o  0.65  0.15  0.43  1.00  Ht. of lowest l i v ei  C  0.28  0.33  0.74  0.23  0.37  1.00  $ of variance i n  F  1.4  31.1  67.0  -1.6  -16.5  81.3  Av.Ht. of lowest  H  7.1  -15.1  44.7  0.9  11.3  48.9  dead branches  C  -3-2  -10.5  63.3  5-7  7.0  59.^  branches  ex-  plained by regress>ion l i v e branches i n Douglas f i r and western hemlock, although i t d i d not p l a y such an important r o l e i n the case of western red cedar. Length of l i v e crown was a l s o studied. The most important v a r i a b l e s were d.b.h., t o t a l height, and crown width/crown diameter.  Linear  - 32 Table 10.  L i n e a r m u l t i p l e r e g r e s s i o n equations f o r height to l i v e  Species  Regression c o e f f i c i e n t s f o r height to l i v e branches (Y) D.b.h. T.Ht. Age BA/acre  Intercept  Douglas f i r  -7.32  Douglas f i r  -12.kk  W. hemlock  0.343  0.288  0.413  0.606  0.230  0.296  -13.42  -0.637  0.622  0.118  W. hemlock  -20.76  -0.274  O.518  0.055  W.r. cedar  0.81  -1.943  0.549  0.251  W.r. cedar  -8.80  -I.367  0.353  0.191  '  0.084  O.095  0.123  branches R  2  (Ft.)  (*)  15.5  74.2  15.0  75-6  13.6  73-5  12.9  70.4  14.2  47.9  13-3  53-9 11.  m u l t i p l e - r e g r e s s i o n equations are given f o r t h i s r e l a t i o n s h i p i n Table Table 11.  Regression equations f o r l i v e crown l e n g t h on D.b.h., T o t a l height and CW/D  Species  Douglas f i r  W. hemlock  W.r. cedar  Intercept  Regression c o e f f i c i e n t s f o r l i v e crown l i v e crown length on: D.b.h. Tot.Ht. CW/D  R  2  (Ft.)  W  -11.9  0.755  0.332  13.1  14  63.3  15-2  0.997  0.193  -  14  60.6  13.1  1.938  4.3  15  58.9  -14.1  O.69I  0.389  14.6  13  58.3  13-5  0.546  0.316  -  14  52.7  10.0  2.090  7-4  15  43.5  -7.0  1.175  0.428  4.5  15  65.7  1.6  1.050  0.417  -  15  65.2  6.7  2.699  2.5  16  57.8  -  -  -  - 33 The percentage of l i v e crown was a l s o analysed, w i t h s e v e r a l variables.  These were d.b.h., t o t a l height, age, s i t e index and b a s a l  area per acre, crown width/diameter length of l i v e branches.  (CW/D),  height/crown width ( H t / C W ) , and  The most s i g n i f i c a n t f a c t o r s i n f l u e n c i n g  percentage of l i v e crown were b a s a l area and height/crown width.  As the  b a s a l area per acre and the r a t i o of tree height to crown width increased, the percentage of l i v e crown decreased.  Linear m u l t i p l e - r e g r e s s i o n  equations are given i n Table 12 below. Table 12.  Regression equations f o r percentage of l i v e crown on b a s a l area per acre and H/CW  Species  Intercept  Regression c o e f f i c i e n t s f o r percentage of l i v e crown on: b a s a l area per acre and H/CW Basal area H/CW  SE  E  R  2  (Ft.)  (*)  Douglas f i r  83  -0.11  -2.3  15  32.3  W. hemlock  98  -0.14  -3.0  15  44.7  W.r. cedar  105  -0.14  -3.6  16  36.8  Relationships among crown width/d.b.h. r a t i o s and d.b.h., age, t o t a l height, s i t e index and crown width were studied by Smith and Ker (i960), and m u l t i p l e regression a n a l y s i s of the data was used on 96 open-growth Douglas f i r and 84 western hemlock open-growth a t Haney.  The a n a l y s i s showed  that the most important v a r i a b l e was d.b.h. f o r estimation of crown width. D.b.h. accounted f o r so much v a r i a t i o n i n both crown width and crown width/ d.b.h. that there was l i t t l e merit to use o f other v a r i a b l e s i n a d d i t i o n to d.b.h.  R e l a t i o n s h i p s between d.b.h. and crown width of f u l l y open Douglas  f i r and western hemlock trees are given i n Table 13•  - 3^ Table 13.  Relationships between Crown Width and D.b.h. of F u l l y Opengrown Douglas f i r and Western Hemlock Trees  Species  Equations  SE  E  No. of trees  Douglas f i r  CW = 5.88 + 1.496 D.b.h.  2.33  96  W. hemlock  CW = 4.23 + 1.423 D.b.h.  2.56  84  0.24  96  0.55  84  Douglas f i r  CW r 2.73 - 0.054 D.b.h. D.b.h.  W. hemlock  CW D.b.h.  a  3.19 - 0.110 D.b.h.  - 35 (1)  INFLUENCE OF STOCKING Well-stocked  stands of Douglas f i r and western hemlock at Haney were  studied by Smith and Ker (i960), t o determine r e l a t i o n s h i p s between crown width and other v a r i a b l e s .  Pope (19^9) and Dilworth (1957) have a l s o determined  r e l a t i o n s h i p s between v i s i b l e crown width and d.b.h. on a number of Douglas f i r growing i n Washington and Oregon.  Their data showed that i n well-stocked  stands the r a t i o of crown width t o d.b.h. i s around one f o r Douglas f i r and western hemlock t r e e s l a r g e r than eight inches i n d.b.h.  For f u l l y open grown  Douglas f i r and western hemlock trees l a r g e r than eight inches i n d.b.h. the r a t i o of crown width to d.b.h. i s about two. Douglas f i r , western hemlock and western red cedar trees were studied in r e l a t i o n to stocking at Haney.  Ratios of crown width/d.b.h. by species  stocking, f o r open and densely grown trees are given i n Table lk. to these data the next conclusion can be drawn.  and  According  The r a t i o of crown width/d.b.h.  was greatest f o r open grown Douglas f i r and smallest f o r densely grown western hemlock.  As d.b.h. increased the r a t i o of CW/d.b.h. decreased f o r a l l three  species independently of density of stocking conditions.  The r a t i o was  greater  f o r a l l three species growing i n open c o n d i t i o n s , than i n dense stocking conditions . During the study i t was a l s o found that the r a t i o of tree height/ crown width was  c l o s e l y r e l a t e d to the r a t i o of tree height and t o average  spacing distance.  Simple c o r r e l a t i o n c o e f f i c i e n t s are given i n Table 15 f o r  height/crown width and crown width/d.b.h.  - 36 Table lk.  Ratios of Crown Width/d.b.h. by species and stocking. Open grown H c  Aveg.D.b.h. in.  F  Densely grown. F H  2  3.4  2.8  3-0  1.7  -  k  2.9  2.3  2-3  1.4  1.1  6  2.4  2.0  1.9  1-3  1.0  8  2.2  1.9  1.8  l.l  1.0  10  2.1  1.9  1-7  1.1  0.9  12  2.0  1.8  1-7  1.0  0.9  lk  1-9  1.7  1.6  1.0  0.9  16  1.8  1-7  1.6  1.0  0.9  18  1.8  1.6  1-5  0.9  0.9  20  1.8  1.6  1-5  0.9  0.8  22  1.7  1.6  1-5  0.9  0.8  2k  1.7  1-5  1.4  0.9  0.8  26  1.7  1.5  1.4  0.9  0.8  Height/crown width values are required t o be, f o r s i g n i f i c a n c e at p .05 percent confidence l e v e l , 0 . l 4 f o r Douglas f i r , 0.15  f o r western hemlock and 0.23 f o r  western red cedar. Basal area has a l s o been studied i n connection w i t h crown width/d.b.h. together w i t h other v a r i a b l e s such as d.b.h., t o t a l height, age, s i t e index and crown width.  Percentages of v a r i a t i o n i n crown width/d.b.h. and s i n g l e  c o r r e c t i o n c o e f f i c i e n t s are given i n Table 16, and western red cedar.  f o r Douglas f i r , western hemlock  Regression equations f o r estimate of crown width/d.b.h.  from height/crown width, or height/crown width form crown width/d.b.h. f o r each of these species are given i n Table  17.  Table 15. Comparison o f c o r r e l a t i o n s between crown width/d.b.h. and h e i g h t / c r o w n width, r a t i o s w i t h e l e v e n v a r i a b l e s f o r Douglas f i r , w e s t e r n hemlock and w e s t e r n r e d cedar.  Species Douglas F i r  W.hemlock  W.r.cedar  Variables  D  Ht.  A.  SI.  cw.  B.A.  CW/D  CC  Ht/CW  io I . e . L.1.c.  CW/d.b.h.  0.60  0.73  0.64  0.35  0.03  0.48  1.00  0.02  0.76  0.49  o.4i  Ht/CW  0.24  0.51  0.49  0.23  0.35  0.48  0.76  0.39  1.00  0.44  0.21  CW/d.b.h.  0.53  O.58  0.58  0.10  0.16  O.50  1.00  0.09  0.76  0.54  0.24  Ht/CW  0.l4  0.48  0.45  0.13  0.45  O.54  O.76  0.25  1.00  0.55  0.12  CW/d.b.h.  O.58  0.54  0.31  0.44  o.o4  0.28  1.00  o.i4  0.71  0.12  o.4i  Ht./CW  0.28  0.53  0.28  0.35  0.27  0.51  0.71  0.06  1.00  0.50  0.22  Where t h e a b b r e v i a t i o n s a r e as f o l l o w s :  D-D.b.h. Ht - H e i g h t A - Age SI - S i t e index CW - crown w i d t h B.A.-basal a r e a  CW/D. CC. Ht/CW $ I.e. L.1.c.  r a t i o o f crown w i d t h t o D.b.h. crown c l a s s r a t i o o f h e i g h t t o crown w i d t h p e r c e n t o f l i v e crown l e n g t h o f l i v e crown.  - 38 Table l 6 .  R e l a t i o n s h i p s among crown width d.b.h., age, t o t a l height, s i t e index, crown width and b a s a l area.  Percentage of v a r i a t i o n i n crown width/d.b.h. explained i n m u l t i p l e regression by:  Species  D.b.h.  Ht.  Age  -21.5  14.8  0.7  -97.4  Douglas f i r ( 0 ) 192.7  SI.  CW.  All  BA.  89.3  0.11  Douglas f i r  58.5  52.3  -25.6  -^•5  - 3-0  2.8  80.5  0.19  W. hemlock  53-3  15.7  - 6.6  -0.8  14.9  6-5  83.3  0.16  W.r. cedar  58.6  14.3  - 3-7  2.8  3-2  1.0  76.2  0.23  Simple c o r r e l a t i o n c o e f f i c i e n t s f o r crown width/ d.b.h. on: Douglas f i r ( O )  -.714  -.673  -.684  -.088  -.489  -  -  Douglas f i r  -.603  -.719  -.636  -.313  -.033  -.479  -  W. hemlock  -.530  -.580  -.581  -.182  -.498  -  -  W.r. cedar  -.582  -.544  -.313  -.435  -.277  -  -  • 159 -.638  Symbol i n Table 16 " 0 " , means "open"  Table 17•  Species  Regression equations f o r estimate of crown width/ d.b.h. from height/crowm width, or height/crown width from crown width/d.b.h., by species.  Intercept  Regression c o e f f i c i e n t s f o r CW/d.b.h. on height/CW  E ft. S E  R  2  1o  Douglas f i r  2.134  -0.164  O.278  57-^  W. hemlock  2.03  -0.144  0.245  57-^  W.r. cedar  2.22  -0.206  0.321  50.4  Regression c o e f f i c i e n t s f o r height/CW on Cw/d.b.h. Douglas f i r  9.83  -3.572  1.30  57-^  W. hemlock  io.4i  -3.976  1.34  57-4  W.r. cedar  7.72  -2.416  1.10  50.4  - 39 (2)  INFLUENCE OF  AGE  The age o f an i n d i v i d u a l t r e e i n f l u e n c e s i t s crown form. t r e e s have n o t developed Douglas about  V e r y young  t h e i r more o r l e s s c h a r a c t e r i s t i c crown form.  Young  f i r , western hemlock and western r e d cedar take on t y p i c a l crown shape  30-35 y e a r s , i f growing w i t h i n dense s t a n d s .  F o r each s p e c i e s  found c h a r a c t e r i s t i c crown forms which are t y p i c a l f o r the v a r i o u s  can be  age  period  o f a t r e e examined.  I t has been observed a t Haney, t h a t the upper p o r t i o n o f a crown changes q u i t e d i f f e r e n t l y from i t s lower p o r t i o n , and s t o c k i n g w i t h i n which the examined t r e e was  grown.  i n d e p e n d e n t l y o f the  T h i s f a c t suggested  dis-  c u s s i o n o f the changes i n crown caused by age, s e p a r a t e l y f o r upper and  lower  portions.  a.  Changes i n upper p o r t i o n o f the crown. E v e r y t r e e s t u d i e d was  s e c t i o n views. trees  (21  shapes was i t was  A f t e r the sketches had been arranged by the age  - kO, kl - 60,  e t c . . . . ) , i t was  i n c r e a s e d by age o f t r e e s .  evident  (Graphs 1,2,3).  hemlock and over 100  cross  groups  By measuring  a n g l e s from the sketches f i r and  y e a r s and f o r western r e d cedar from 30 t o 100  I n c r e a s e i n t o p - a n g l e over 130 y e a r s o f age  of  t h a t the t o p angle o f crown  found t h a t the changes i n a n g l e were l i n e a r f o r Douglas  hemlock from 30 t o 130 age  drawn i n d i v i d u a l l y i n p r o f i l e and  i n Douglas  fir,  western years of  western  i n the western r e d cedar i s n o t as r a p i d as i n  youth.  The  curve a l s o shows t h a t as the t r e e approaches  top becomes almost f l a t t e n e d .  i t s m a t u r i t y the  Average t o p - a n g l e v a l u e s w i t h t h e i r s t a n d a r d  d e v i a t i o n s are p r e s e n t e d i n T a b l e 18,  f o r Douglas  western r e d cedar t r e e s by d i f f e r e n t age  groups.  f i r , western hemlock and The average  top-angle v a l u e s  To f o l l o w page 39  80  Age Graph I  in Years  Average top angles over age for Douglas fir  80  L_< <  I  I  I  I  I  30  50  70  90  110  Age in Years  Graph I Average top angles over age for Douglas fir  L_ 130  Age in Years  Graph 2 Average top angles over age for Western hemlock  - ko -  i n some cases have been f o u n d s u f f i c i e n t l y t y p i c a l t o d i s t i n g u i s h i n d i v i d u a l s p e c i e s i n c e r t a i n age groups.  U n f o r t u n a t e l y , i n t h e m a j o r i t y o f t h e cases  t h e r e was such a g r e a t o v e r l a p i n these v a l u e s t h a t i t was h a r d l y p o s s i b l e t o use t h e t e c h n i q u e i n s e p a r a t i o n o f s p e c i e s .  The o v e r l a p o f v a l u e s was found  t o be t h e l a r g e s t i n w e s t e r n hemlock and w e s t e r n r e d c e d a r . T a b l e 18.  Average t o p - a n g l e v a l u e s w i t h t h e i r s t a n d a r d d e v i a t i o n s f o r Douglas f i r , w e s t e r n hemlock and w e s t e r n r e d c e d a r . Age c l a s s ( Y r s . )  21-40  41-60  61-80  81-100  101-120  121-  48  12  59  10  11  44  4  53  57  63  65  73  Douglas f i r No.of t r e e s Avg.top-angle  °  9  S t a n d . Dev. °  12.7  Range o  25-60  9-2  7-7  9-7  4.1  3-8  40-65  45-67  50-70  55-75  70-89  W. hemlock No. o f t r e e s  38  6  ^7  27  10  36  Avg. t o p - a n g l e °  27  35  43  49  5^  57  11.2  11.5  11.6  25-37  33-45  43-56  9-1  S t a n d . Dev. °  15-28  Range °  3-6  3-9  50-67  61-80  W. r . cedar No. o f t r e e s Avg.top-angle S t a n d . Dev. ° Range °  °  18  5  21  7  -  37  27  35  48  55  -  lh  13-9  -  5-2  57-75  -  67-83  8.4l  9.8  10.5  15-35  29-4o  36-51  '  - in Another c h a r a c t e r i s t i c f i g u r e was found f o r each species, the quot i e n t of average top-angle and average crown height.  Figures are presented  i n Table 19. Table 19.  Quotient of average top-angle and average crown height f o r Douglas f i r , western hemlock, and western red cedar. Age classes (Yrs.) 81--120 61-80  101-120  121-  21-40  41--6o  Douglas f i r  1.20  0 96  0.60  0 50  0.45  0.45  W. hemlock  1.50  0 TO  0.54  0 52  0.47  0.42  W.r. cedar  1.45  0 92  0.71  0 68  -  0.49  Species  As has been p r e v i o u s l y mentioned, each recorded crown shape was compared w i t h a shape-scale.  The e f f e c t of age can be pointed out very d i s t -  i n c t l y i n t h i s way, since the top of crowns of each species become wider with age.  The data of t h i s survey are presented i n Table 20.  The frequency of  appearance of species i n respective crown shape-scale and age c l a s s i s expressed i n percentages. Table 20.  Shape  D i s t r i b u t i o n of crown shapes of Douglas f i r ( F ) , western hemlock ( H ) , and western red cedar (C) 20^40 F H C  4o-6o F  H  Age Classes (Yrs. ) 61-80 C F H C  F  81-100 H C  Percentage of t o t a l number of t r e e s i n each species and age c l a s s Linear  -  6  12  -  -  -  8  4  -  -  8  -  Oblong  12  6  12  20  8  24  5  6  25  -  -  -  Lanceolate 34  6  35  26  20  9  14  4  10  -  -  14  Oblanceolate 12 Ovate 9  -  18  -  -  34  19  18  15 25  -  -  17 38  -  27  7 4o  8  14  Obovate  -  -  -  7  -  -  23  -  -  -  Elliptical  -  -  -  -  -  12  -  10  -  -  -  14  28  4l  17  -  38  -  18  19  10  -  19  43  Rhomboid  5  -  -  -  -  8  -  10  -  -  15  Irregular  -  14  6  -  -  -  5  39  5  -  65  -  Deltoid  100 /olOOfo LOO/o  100#100#100#  lOOfolOO/olOO/o  -  " . - lOO/olOOfo  - k2  -  b. Changes i n l o w e r p o r t i o n o f the crown. The- e f f e c t o f age on t h e l o w e r p o r t i o n o f t h e crown i s not uous u n t i l n a t u r a l p r u n i n g s t a r t s .  conspic-  The b e g i n n i n g o f the n a t u r a l p r u n i n g may  be  seen i n d e a t h o f t h e l o w e s t branches a t about 25 y e a r s i n Douglas f i r , 30 y e a r s i n w e s t e r n hemlock, and 35 y e a r s i n w e s t e r n r e d c e d a r , growing i n normal c o n d i t i o n s a t Haney.  The e f f e c t o f age, however, on t h e l o w e r p o r t i o n i n  c o n t r a s t w i t h the.upper p o r t i o n o f t h e crown w i l l show up d i s t i n c l y o n l y a t 6 l - 8 0 y e a r s o f age, when b r a n c h s i z e s and t h e d i s t a n c e s between them are q u i t e large.  The ends o f l o w e r branches o f mature Douglas f i r w i l l p o i n t down, i n  c o n t r a s t w i t h young Douglas f i r t r e e s , where t h e l o w e r branches w i l l upward. downward.  The l o w e r branches o f hemlock and cedar t r e e s w i l l l e a n e x t r e m e l y These f a c t o r s can be seen most p r o m i n e n t l y when t h e t r e e s o f t h e s e  species r e a c h t h e i r mature age (Appendix I a.p.; (3)  point  I l l a. & f . ) .  INFLUENCE OF ELEVATION I n f l u e n c e s o f e l e v a t i o n on crown shape o f t r e e s has been observed Rohmeder and Schonbach (1959) have d i f f e r e n t i a t e d  by s e v e r a l a u t h o r s a l r e a d y .  t h r e e v a r i a t i o n s i n crown o f Norway s p r u c e , ( P i c e a e x c e l s a ) , i n the German A l p s . An e f f e c t o f e l e v a t i o n has been observed a l s o i n C o a s t a l Douglas f i r , found i n t h e v i c i n i t y o f Haney and Vancouver.  I f a Douglas f i r i s growing o v e r 2,000-  2,500 f e e t e l e v a t i o n i t s crown w i l l appear much narrower t h a n t h a t o f a s i m i l a r t r e e growing near sea l e v e l .  The d i f f e r e n c e s i n t h e two crown t y p e s w i l l  most d i s t i n c t l y i n t h e upper p o r t i o n o f t h e crown.  Douglas-fir trees  appear  growing  a t h i g h e r e l e v a t i o n s w i l l have a n a r r o w e r , and more p o i n t e d t o p s t h a n t h o s e growing i n l o w e r l a n d s , w h i c h w i l l have a s h o r t e r t i p w i t h a f l a t t e r t o p - a n g l e (Appendix I h . i . j . k . l . ) .  These d i f f e r e n c e s are most e v i d e n t i n D o u g l a s - f i r  t r e e s a t ages o f about kO t o 100 trees.  y e a r s , and are not so n o t i c e a b l e i n mature  - k-3 The d i f f e r e n c e s i n crown shapes may be e x p l a i n e d m a i n l y by d i f f e r ences i n weather and p r e c i p i t a t i o n between l o w and h i g h e l e v a t i o n s . the more s e v e r e w i n t e r and -the g r e a t e r amount o f snow a t h i g h e r f o r c e t h e t r e e s t o d e v e l o p a narrow crown.  Possibly  elevations  T r e e s w i t h narrow crowns would n o t  h o l d up as much snow t h a n t h o s e w i t h w i d e r crowns and would s u f f e r l e s s breakage from e x c e s s i v e  l o a d s o f snow.  S t r i c t r u l e s i n t h i s m a t t e r cannot be s e t up,  because i t o f t e n happens t h a t t r e e s w i t h two q u i t e d i f f e r e n t crown t y p e s w i l l be found s i d e by s i d e (Appendix I f . ) . The d i f f e r e n c e s i n f r e q u e n c y , however, of t h e s e two crown t y p e s o f D o u g l a s - f i r t r e e s a r e e v i d e n t .  No d i f f e r e n c e s i n crown shapes o f w e s t e r n hemlock and w e s t e r n r e d cedar t r e e s c o u l d be a t t r i b u t e d t o d i f f e r e n c e s i n e l e v a t i o n .  - kk -  PHOTO FACTORS WHICH FACILITATE SPECIES IDENTIFICATION  VALUE OF TONE 1.  The importance of tone t o the f o r e s t i n t e r p r e t e r . Tone i s a f u n c t i o n of the b r i l l i a n c e of l i g h t r e f l e c t e d from  the  subject, which appears on black and white photographs as the range of  gray from black through t o the white.  To i d e n t i f y an object the i n t e r -  preter uses the p i c t o r i a l q u a l i t i e s i n i t s r e c o g n i t i o n .  Among the  p i c t o r i a l q u a l i t i e s there are only four forms of information a v a i l a b l e f o r the i n t e r p r e t e r of a e r i a l photographs:  shape ( i n c l u d i n g s i z e ) , t e x t u r e ,  shadow p a t t e r n , and tone. Among these c h a r a c t e r i s t i c s , i n most cases, the tone of an image i s used i n i t s r e c o g n i t i o n . An image has a shape, but the shape i s only shown by a tone at i t s edges that d i f f e r s from the tone of i t s background.  I t has been proven  that the o p t i c a l nerves of the human eyes respond only t o changes i n i l l u m i n a t i o n (Katz 1950).  I t f o l l o w s then that the boundaries of the  images give the eye i t s most intense impression. The i n t e r p r e t e r requires therefore a d i s t i n c t change i n the tone of the edges of images, t o c a l l his a t t e n t i o n t o the. existence of those images.  This i s the f i r s t step  i n i d e n t i f i c a t i o n of images and t h i s i s the place i n which' r e s o l u t i o n i s of the f i r s t importance. However, once the i n t e r p r e t e r has recognized the existence of an image, i t i s e s s e n t i a l t o take i n t o consideration the tone of the whole image area and of the surroundings of the examined object, before the  - 45 -  image i t s e l f can be recognized. Through, t h i s p r e l i m i n a r y examination, which i s not d i r e c t e d on the subject i t s e l f , but on i t s surroundings, i n v o l v i n g the comparison of tone, size and texture d i f f e r e n c e s and examination of environment, the i n t e r p r e t e r can gain a large amount of information about the object i t s e l f which may be very valuable clues i n i t s recognition.  P a r t i c u l a r l y important i n the f i e l d of forestry^,- i s the  separation of timber stands from bogs and meadow by t o n a l d i f f e r e n c e s of images.  I n c l a s s i f i c a t i o n of the stands, tone i s an indispensable  character, and w i t h i n the c l a s s i f i e d stand, or i n an open p o s i t i o n , the tone may give the f i n a l separation of some i n d i v i d u a l tree species, such as Douglas f i r from western r e d cedar, where the l a s t one appears always the  l i g h t e r tone.  2.  Factors c o n t r o l l i n g the tone of an object. I t can be stated generally that the tone of an image on a  photo depends on the amount and the q u a l i t y of l i g h t r e f l e c t e d from the object t o the l i g h t , s e n s i t i v e m a t e r i a l .  According t o t h i s , as more l i g h t  i s r e f l e c t e d from an object, i t s image tone w i l l be l i g h t e r , and objects which absorb much l i g h t w i l l have a dark tone on a photograph.  Then the  tone of one image i s c o n t r o l l e d mainly by the colour of the surface, the nature of surface of the objects and the amount of haze i n the a i r .  In  a d d i t i o n there are three more f a c t o r s which l a r g e l y c o n t r o l the tone of photographs.  These are l o c a l topography, kind of camera, and p o s i t i o n of  the sun. a.  Colour of surface. I t i s known generally that the l i g h t e r the colour of an object,  - 46 the more l i g h t i s r e f l e c t e d from i t s surface.  But two s i m i l a r l y green  objects, i n our case t r e e s , may appear on photos w i t h a d i f f e r e n t tone. With leaves hanging at various angles from the twigs, or i n the case of evergreens, standing out around the t w i g , and viewing i n d i v i d u a l t r e e s from d i f f e r e n t angles on d i f f e r e n t parts of photos, there i s an appreciable v a r i a t i o n i n the colour of given species on one photo, even assuming that every tree of that species i s i n the same p h y s i o l o g i c a l state.  The v a r i a t i o n s i n tone w i t h i n photographs are due t o the angle of  view and amount of shadowed and s u n - l i t portions of the tree examined. There might be some s l i g h t d i f f e r e n c e s i n p h y s i o l o g i c a l s t a t e , r e l a t e d t o s i t e c o n d i t i o n s , or attack of insects and disease, but the detection of these d i f f e r e n c e s would require more extensive examination of species on the whole area, which f a l l s beyond the scope of t h i s study. As was mentioned above, the tone v a r i e s w i t h the amount of r e f l e c t i o n , but the r e f l e c t i o n may l a r g e l y depend on the angle of viewing of the l i g h t . (Wallis  The r e s u l t s of such an experiment are shown i n Table 21  1943).  Table 21.  Changes i n r e f l e c t e d l i g h t caused by angle of viewing.  Incidence  0  0  45  incidence 0  45  Leaf viewed from  150  0  incidence  50  Percent of r e f l e c t e d l i g h t from surface of a mulberry l e a f . Blue Green Red  23.1  14.0  35-8  25.O  39.3  35-7  Examination of the leaves of various species shows there i s p r a c t i c a l l y no v a r i a t i o n i n the way they r e f l e c t v i s i b l e r e d l i g h t .  The  s i t u a t i o n regarding the r e f l e c t e d green l i g h t i s quite d i f f e r e n t as i t can  - 47 be c l e a r l y r e a l i z e d by examination of mixed stands.  I t i s due t o the  v a r i a t i o n of green colour a l l the way from yellow-green t o dark bluegreen. b.  Nature of surface.  Glossy surface.  The percentage of i n c i d e n t l i g h t r e f l e c t e d t o the camera  depends l a r g e l y upon the smoothness of the r e f l e c t i n g surface, and i n the case of very smooth surfaces, the angles of incidence and r e f l e c t i o n . Water on a calm day i s an i d e a l example of a smooth surface. I f the angle of the sun and camera t o the water surface i s such that the rays of the sun are not r e f l e c t e d d i r e c t l y t o the camera, the water w i l l appear white.  I t f o l l o w s that the photographhic image of water i s e i t h e r  very l i g h t or very dark.  This c o n d i t i o n i s common also i n i n t e r p r e t a t i o n  of f o r e s t type, p a r t i c u l a r l y when i t i s necessary t o d e a l with deciduous f o r e s t type, or other species which have glossy leaves. Rough surfaces.  Rough surfaces vary very l i t t l e i n t h e i r photographic tone  w i t h changes i n angles of incidence and r e f l e c t i o n .  The tone of images of  glossy surfaces i s influenced mainly by the base colour of the object.  In  general, however, they are intermediate i n tone, due t o the d i s p e r s i o n of much of the l i g h t they r e c e i v e .  There are, however, some parts of the  i r r e g u l a r surface which r e f l e c t l i g h t t o the camera.  I n such cases when  d i s p e r s i o n and r e f l e c t i o n of l i g h t are caused on the same surface, the e f f e c t of "contained shadow" w i l l appear (Wallis.-1943)•  This i s the e f f e c t  of innumerable small shadows of the protuberances and dents of the surface which are too small t o r e g i s t e r i n d i v i d u a l l y , because they exceed the l i m i t of r e s o l u t i o n .  The degree of darkening w i l l depend upon the density of  such shadows and t h e i r shadowed area.  - kd C o n t a i n e d shadows a r e the c h i e f r e a s o n f o r t h e d a r k e r tone of  softwoods compared t o hardwoods.  Each i n d i v i d u a l n e e d l e i n t h e  crown  causes a t i n y shadow, because t h e y are q u i t e s e p a r a t e and t h e c u m u l a t i v e e f f e c t i s t o darken t h e a r e a o c c u p i e d by t h e image of t h e crown.  With  hardwoods, t h e much l a r g e r l e a v e s o v e r l a p w i t h few shadows and f o r m a r e l a t i v e l y smooth s u r f a c e w h i c h always appears  lighter.  C o n t a i n e d shadow i s v e r y u s e f u l i n s e p a r a t i o n of undergrowth The t a l l e r  and t h i c k e r the undergrowth, t h e d a r k e r w i l l be i t s tone on  photographs. c.  Haze. Haze c o n s i s t s c h i e f l y of d u s t , smoke and w a t e r p a r t i c l e s .  It  c o n s i d e r a b l y d e c r e a s e s t h e v i s i b i l i t y of an o b j e c t on p h o t o s and r e d u c e s b o t h t h e hue and b r i g h t n e s s , due t o the e f f e c t of q u a l i t a t i v e q u a n t i t a t i v e changes i n t h e l i g h t r e c e i v e d by t h e  and  camera.  Q u a l i t a t i v e l y , haze s c a t t e r s t h e b l u e l i g h t , t h u s r e d u c i n g the  amount of b l u e l i g h t r e a c h i n g t h e o b j e c t s photographed and r e d u c i n g i t  a g a i n when r e f l e c t e d f r o m t h e o b j e c t t o t h e camera.  The r e s u l t of t h i s  event i s t h a t g e n e r a l l y more b l u e l i g h t r e a c h e s t h e camera, w h i c h g i v e s a b l u i s h c a s t i n c o l o r p h o t o g r a p h s , and reduces c o n t r a s t i n b l a c k and w h i t e photos.  W i t h l i g h t haze, a y e l l o w f i l t e r w i l l p e r m i t photography and g i v e s  b e t t e r tone r e n d e r i n g , as f a r as s p e c t r a l e f f e c t s are c o n s i d e r e d . the  Generally,  c h o i c e of f i l t e r depends upon t h e amount of haze, t h e t y p e of f i l m b e i n g  u s e d and the- d e s i r e d t o n e .  The more b l u e l i g h t t h e f i l t e r c u t s o u t , t h e  b e t t e r w i l l be t h e haze p e n e t r a t i o n .  The a t m o s p h e r i c haze a f f e c t s t h e r e f l e c t i o n of l i g h t  quantitatively  - k^ a l s o , which acts against rendering ing  of good t o n e .  The  amount of l i g h t  t h e o b j e c t b e i n g photographed ( t h i s i s v e r y much t r u e when t h e  reach-  object  photographed i s a f o r e s t s t a n d ) , i s r e d u c e d so much t h a t t h e c o n t r a s t tween shadow and  l i g h t e d p o r t i o n s of an o b j e c t i s h i g h l y s o f t e n e d .  extreme cases the shadow may  disappear completely,  d i f f e r e n c e s between hardwoods and d.  softwoods may  be  be-  In  and even the wide tone lost.  T op ography. On h i l l y l a n d , the sun may  sunny s i d e of the h i l l and the o t h e r  r e f l e c t o f f o n l y t h e t r e e s on  the  s i d e of the h i l l w i l l be shady.  This  d i f f e r e n c e i n exposure w i l l , of c o u r s e , cause some t o n a l d i f f e r e n c e s on photo a l s o ; t h e  stand on the sunny s i d e of the h i l l w i l l appear l i g h t e r  because f i l m i s a f f e c t e d by t h e g r e a t e r amount of l i g h t energy s h i n i n g the t r e e crowns, t h a n on t h e l e s s w e l l l i g h t e d s i d e of t h e e.  the  on  hill.  Camera. T h i s f a c t o r o r i g i n a t e s f r o m t h e n a t u r e of l e n s e s u s e d i n the  camera.  Some l e n s e s t e n d t o admit more l i g h t t h r o u g h t h e i r c e n t e r  than through t h e i r p e r i p h e r a l p o r t i o n s . w i l l be d a r k e r  Therefore,  portion  the edges of p h o t o s  and t h e i r c e n t e r p o r t i o n w i l l r e g i s t e r i n l i g h t e r t o n e .  v a r i a t i o n i n tone may  be  l i m i t e d by a t h i n b l u e cover around the  p o r t i o n of the l e n s , or w i t h a m u l t i p l e l e n s system combined w i t h  This  peripheral flat  plates.  f.  P o s i t i o n of t h e  sun.  T a k i n g photographs over a f l a t a r e a , the t r e e s away f r o m the sun w i l l r e g i s t e r i n l i g h t e r t o n e s t h a n t h o s e t o w a r d the  sun.  One  of  r e a s o n s i s t h a t t r e e s away f r o m t h e sun w i l l c a t c h more s u n l i g h t and i t t o the camera, t h a n the o t h e r s w h i c h are toward the sun.  the reflect  Another reason  - 50 -  i s t h a t t h e g r e a t e r t h e d i s t a n c e t h e sun's r a y s t r a v e l t h r o u g h t h e atmosp h e r e , the g r e a t e r w i l l be t h e haze e f f e c t .  A c c o r d i n g t o t h i s , as the  sun's e l e v a t i o n d e c r e a s e s , t h e e f f e c t of t h e haze i n c r e a s e s . A v a r i a t i o n i n t h e sun's e l e v a t i o n w i l l a l s o a f f e c t the amount of l i g h t r e f l e c t e d up f r o m t h e ground.  The  c l o s e r the ground s u r f a c e i s  o t o f o r m i n g a 90  angle t o t h e sun's r a y s , t h e s m a l l e r w i l l be the shadows  of i r r e g u l a r i t i e s , and t h e r e f o r e t h e more l i g h t ground w i l l r e f l e c t t o a v e r t i c a l camera. 3.  Measurement of t o n e . The measurement of tone can be done i n two ways: a.  by u n a i d e d eye, and b. a.  Measurement by  R e c o g n i t i o n by u n a i d e d The  Recognition  comparison.  eye.  o n l y work d e a l i n g d i r e c t l y w i t h the q u e s t i o n of the number  of t o n e s r e c o g n i z a b l e i n a e r i a l photographs w i t h o u t a i d s of any k i n d , t h a t has come t o the w r i t e r ' s a t t e n t i o n , i s t h a t of L e i g h t o n ( l 9 ^ l ) . s e r i e s of t e s t s he t r i e d t o s e p a r a t e images w i t h d i f f e r e n t  In h i s  reflection  d e n s i t y , i . e . , images a p p e a r i n g w i t h d i f f e r e n t t o n e , and p o i n t e d out t h a t t h e r e must be a g r e a t range i n r e f l e c t i o n d e n s i t i e s of images t o d i s c e r n them, and t o be a b l e t o s e p a r a t e them. shown i n T a b l e  The  r e s u l t s of h i s experiment are  22.  There were two o b s e r v e r s  chosen.  A, almost  completely  i n e x p e r i e n c e d i n i n t e r p r e t a t i o n , and B, an i n t e r p r e t e r w i t h s e v e r a l y e a r s of e x p e r i e n c e .  B o t h had t o separate e q u a l numbers of p l a t e s of d i f f e r e n t  hues of t o n e , w i t h o u t any r e f e r e n c e or comparison.  - 51 -  T a b l e 22.  Human a b i l i t y i n s e p a r a t i o n of d i f f e r e n t  Obser- T o t a l S t e p s ver No. of I d e n t i f i e d steps c o r r e c t l y  of E r r o r s i n v a r i o u s C l a s s e s Density Differences  A  kk  21  B  kk  29  .00 - . 0 6 - . 1 0 - .16- .21- .26- .31 .05 .10 • 15 .20 • 25 •30 .35 2 1 3 1 7 9 2 2 k 1 6 -  Totals  88  50  13  To ensure 95$ experienced 0.21  No.  tones.  11  3  k  3  3  1  success i n i d e n t i f y i n g tone under such, g i v e n c o n d i t i o n s , t h e i n t e r p r e t e r B would r e q u i r e a d e n s i t y d i f f e r e n c e i n tone of  o r more, and the i n e x p e r i e n c e d 0.31  more v a l u a b l e when T a b l e 23  or more.  i s examined.  These f i g u r e s become  According t o t h i s t a b l e , the  f i g u r e s show t h a t i n t e r p r e t e r A c o u l d s e p a r a t e a shadowed w h i t e p i n e f r o m a shadowed w h i t e spruce o n l y w i t h d i f f i c u l t y , because the d i f f e r e n c e between these two  s p e c i e s i n r e f l e c t i o n d e n s i t y i s o n l y 0.10.  I n Table  23,  some v a l u e s of r e f l e c t i o n d e n s i t i e s are g i v e n f o r s e v e r a l t r e e s p e c i e s o b t a i n e d f r o m s e t s of f a l l photos on p a n c h r o m a t i c f i l m w i t h RF of and g l o s s y f i n i s h (Losee T a b l e 23.  1  : 7>500  1951)•  R e f l e c t e d l i g h t d e n s i t i e s f r o m l e a v e s of some C o n i f e r o u s Deciduous s p e c i e s . S p e c i e s  Reflected densities.  White b i r c h and aspen ( s u n l i g h t s i d e )  o.ok  White p i n e , r e d p i n e ( s u n l i g h t s i d e )  0.54  White sp r u c e ( s u n l i g h t s i d e )  0.84  B l a c k spruce  1.25  (shadowed and s u n l i g h t s i d e s i n u n r e s o l v e d complex)  White p i n e (shadowed s i d e )  and  1.35  - 52 2.  Measurement by comparison. I n d e a l i n g w i t h o b j e c t i d e n t i f i c a t i o n of a e r i a l p h o t o g r a p h s ,  r e c o g n i t i o n keys a r e i n d i s p e n s a b l e .  Such r e c o g n i t i o n keys a r e u s u a l l y  made up of s e v e r a l f u n d a m e n t a l f a c t o r s : t o n e , t e x t u r e , shape, shadow p a t t e r n , g e n e r a l appearance, and d i s t r i b u t i o n .  A l l of t h e s e f a c t o r s ,  except tone and i n some cases t e x t u r e t o o , can be d i s c u s s e d w i t h c o n c r e t e terminology.  Tone r e f e r s t o t h e b r i l l i a n c e w i t h w h i c h l i g h t i s r e f l e c t e d  by an o b j e c t .  O b j e c t s w i t h d i f f e r e n t b r i l l i a n c e w i l l have d i f f e r e n t t o n e .  On c o n v e n t i o n a l b l a c k and w h i t e p h o t o s , t h e tone i s r e g i s t e r e d i n v a r y i n g shades of g r e y .  I n many r e c o g n i t i o n k e y s , t h e tone i s c l a s s i f i e d by words  such as d a r k , medium or l i g h t , e t c .  I t i s o b v i o u s t h a t what might be  medium tone t o one o b s e r v e r would n o t n e c e s s a r i l y be so c o n s i d e r e d by a second o b s e r v e r .  I n d e s c r i b i n g t h e c h a r a c t e r i s t i c tone of c e r t a i n p h o t o -  g r a p h i c images i t i s u s e f u l t o make a r e f e r e n c e t o a s t a n d a r d "grey s c a l e " , w h i c h i s shown i n F i g .  5  (Colwell  F i g . 5.  1952).  Tone s c a l e .  Such a s c a l e of tone was u s e d i n d e s c r i p t i o n s of tone changes of Douglas f i r , w e s t e r n hemlock, and w e s t e r n cedar on d i f f e r e n t s c a l e s of photos.  I t might be w e l l t o mention t h a t , i f t h e t e n degrees of tone  q u a l i t y a r e c u t a p a r t and mounted on s e p a r a t e s t r i p s of l i g h t c a r d b o a r d , comparison under t h e s t e r e o s c o p e would be f a c i l i t a t e d .  Such a tone s c a l e  -  53-  s h o u l d become s t a n d a r d equipment f o r i n t e r p r e t e r s of a e r i a l  3-  Changes i n tone caused by s c a l e of  photos.  photos.  A l o g i c a l approach t o the d i f f e r e n t i a t i o n of t r e e s p e c i e s  on  a e r i a l p h o t o s would be the d e t e r m i n a t i o n of the d i f f e r e n t t o n e s produced by t h e s p e c i e s t o be d i f f e r e n t i a t e d .  I t i s l o g i c a l because the n a t u r a l  appearance of mixed f o r e s t and a l s o d i f f e r e n t i n d i v i d u a l t r e e s p e c i e s does show up c o n s i d e r a b l e v a r i a t i o n i n hue  and b r i g h t n e s s .  A l l the c o n i f e r s are  d a r k e r t h a n t h e d e c i d u o u s t r e e s , and l i s t s of t h e s e and o t h e r s p e c i e s c o u l d be made r a n g i n g f r o m the d a r k e s t t o l i g h t e s t .  intermediate I f t h e tone  would be s u f f i c i e n t l y c o n s t a n t f o r a g i v e n s p e c i e s , t h e n t h e i n t e r p r e t e r s would have t o measure and compare o n l y t h e t o n e s assuming t h a t a l l the a v a i l a b l e p h o t o s are the same q u a l i t y .  The f i r s t o b s t a c l e , however, comes f r o m what has been i n d i c a t e d i n previous paragraphs, to  t h a t the b r i g h t n e s s , hue and haze are t o o v a r i a b l e  s e t up such a s c a l e of t o n e s f o r d i f f e r e n t s p e c i e s t o be used as a  r e l i a b l e s t a n d a r d key f o r s p e c i e s i d e n t i f i c a t i o n .  J u s t t o mention a  few  such o b s t a c l e s , i t i s known t h a t t h e tone of a g i v e n s p e c i e s v a r i e s w i t h t h e l o c a t i o n r e l a t i v e t o .the c e n t e r of the p h o t o g r a p h , b e i n g d a r k e r a t t h e edges.  V a r i a t i o n s i n tone a l s o can be caused p a r t i a l l y by p r i n t i n g .  The  tone v a l u e s , under such c o n d i t i o n s , w i l l always be r e l a t i v e v a l u e s .  During the examination on d i f f e r e n t s c a l e of p h o t o s ,  of changes i n tone of d i f f e r e n t  species  i t has been f o u n d t h a t t h e d i f f e r e n c e s i n  tone were caused not o n l y by the p r e v i o u s l y d e s c r i b e d r e a s o n s , but by scale also. page 17 ) .  There were f i v e d i f f e r e n t k i n d s of p h o t o s a v a i l a b l e (see  the  -4 5  The  s u r v e y i n v o l v e d the e x a m i n a t i o n of t w e n t y  individual  t r e e s of t h e t h r e e major s p e c i e s of B.C.'s c o a s t a l f o r e s t s : Douglas w e s t e r n hemlock and w e s t e r n r e d c e d a r . were o l d growth.  fir,  Ten t r e e s were young growth and t e n  They were chosen randomly f r o m a group of t r e e s e a s i l y  v i s i b l e on a l l p h o t o s .  E v e r y t r e e was examined i n d i v i d u a l l y on each p h o t o ,  and e v e r y r e c o g n i t i o n f a c t o r was  s t u d i e d under t h e s t e r e o s c o p e .  Unfortunately  t h e tone of each t r e e s p e c i e s c o u l d not be compared d i r e c t l y w i t h each o t h e r , because t h e s p e c i f i c a t i o n s of a v a i l a b l e photos were not i d e n t i c a l . of a number on a tone s c a l e , words have been u s e d f o r tone i n t h i s s u r v e y a s , Medium ( M ) , Medium l i g h t  Instead  classification  (ML), Medium d a r k (MD), e t c .  These l e t t e r s r e p r e s e n t numbers on t h e tone s c a l e as f o l l o w s : 1-2  Very l i g h t  (VL)  3-4  Light  5  Medium l i g h t  6  Medium ( M )  7-8  Medium d a r k  9  Dark  10  Very dark  (L) (ML)  (MD)  (D) (VD)  The r e s u l t s of t h e s u r v e y a r e g i v e n i n T a b l e s 24,  25 and  26.  E x a m i n i n g t h e g i v e n t a b l e s , t h e f o l l o w i n g c o n c l u s i o n s can be drawn: Changes i n tone of young Douglas f i r are caused by d e c r e a s e of photo s c a l e .  As t h e s c a l e of p h o t o s i s d e c r e a s e d , t h e tone i s changed  Medium ( M ) t o Medium l i g h t (ML).  from  T h i s change i n tone was n o t t h e same f o r  o l d growth Douglas f i r , where t h e changes i n tone were i n t h e o p p o s i t e  - 55 direction.  As t h e photo s c a l e was d e c r e a s e d , t h e tone changed f r o m  l i g h t e r t o d a r k e r , f r o m Medium (M) t o Dark ( D ) . Changes i n tone of young and o l d w e s t e r n hemlock a r e t h e same. As t h e p h o t o s c a l e d e c r e a s e s t h e tone changes f r o m d a r k e r t o l i g h t e r , f r o m Medium ( M ) t o Medium l i g h t (ML.) i n young growth, and f r o m Medium d a r k (MD) t o Medium l i g h t  (ML) i n o l d growth.  Changes i n tone of young and o l d w e s t e r n r e d cedar a l s o have "been f o u n d .  As t h e photo s c a l e was d e c r e a s e d t h e tone became l i g h t e r , i . e .  f r o m Medium l i g h t  (ML) t o V e r y l i g h t ( V L ) .  The p e r c e n t a g e s g i v e n i n t h e t a b l e s mean t h e number o f t r e e s c o r r e s p o n d i n g t o t h e tone s c a l e .  F o r example, kO^o i n T a b l e 2k means  t h a t f o u r t r e e s out of t e n o c c u r r e d w i t h Medium ( M ) t o n e .  A similar  p r o c e d u r e has been f o l l o w e d f o r a l l t h r e e s p e c i e s .  Douglas f i r and w e s t e r n hemlock have i n t e r m e d i a t e tone on b l a c k and w h i t e p h o t o s ; u n f o r t u n a t e l y t h e ranges of t o n e s i n many cases o v e r l a p , a l t h o u g h i n some cases t h e y a r e t y p i c a l and t h e two s p e c i e s can be s e g r e g a t e d by t h e tone a l o n e .  The wide range of o v e r l a p i n tone of t h e s e  two s p e c i e s may be e x p l a i n e d by s p e c t r a l a n a l y s i s of t h e f o l i a g e , a c c o r d i n g t o w h i c h t h e d i f f e r e n c e s i n r e f l e c t i o n between two s p e c i e s i s o f t e n s m a l l e r t h a n t h e d i f f e r e n c e between two p l a n t s of t h e same s p e c i e s ( H i n d l e y and Smith  1957)-  Many c h a r a c t e r i s t i c s of t r e e s , such as t h e i r age, y i g o r and  genetic c o n s t i t u t i o n , contribute t o differences i n l i g h t  reflectance.  - 56 T a b l e 24. Photo  Changes i n tone o f Douglas f i r on d i f f e r e n t s c a l e s o f p h o t o s .  scale  T o n e VL  L  s c a l e  ML Y o u  MD  M  n g  D  g r o w t h  P e r c e n t o f t r e e s i n tone c l a s s 330  -  ft./in.  720 ft./in. 1,200 ft./in. 1,500 ft./in. 2,4-00 f t . / i n .  •  -  -  -  -  10 10 30 10 10  20 40 40  70 70 01  1,200  ft./in.  _  1,500  ft./in. ft./in.  -  2,400  T a b l e 25. Photo  d  -  -  30 30  _  -  -  10 f_  g r o w t h  10 10  _  4o 20 30 10 20 80 20 10  10 70 10  _  10 70  Changes i n tone o f w e s t e r n hemlock on d i f f e r e n t s c a l e o f p h o t o s .  scale  T o n e VL  L  s c a l e ML .  Y o u  n iI  M  MD  D  g r o w t h  P e r c e n t of t r e e s i n tone c l a s s 330  ft./in.  .,  720 ft./in. 1,200 ft./in. 1,500 ft./in. 2,400 f t / i n .  -  -  10 10 10 20  20 20 50 50  -  6o  01 1,200 1,500  2,400  ft./in. ft./in. ft./in.  _  -  d  30  30 -  20-  _  -  10  -  80 -  20 -  g r o w t h _  -  40 70 20 30  70 80  _  30 20  -  - 57 -  T a b l e 26.  Changes i n tone o f w e s t e r n r e d cedar on d i f f e r e n t scale o f photos.  T o n e  Photo scale  VL  L  330 720 1,200 1,500  2,400  ft/in ft/in ft/in ft/in ft/in  -  ho  70 80  20 20 6o 30 20 0 1  330 720 1,200 1,500  2,400  ft/in  _  _  ft/in ft/in ft/in ft/in  -  10 70 30 20  10 70 80  Legend:  VL - V e r y L  light  - Light  ML - Medium l i g h t M  - Medium  MD - Medium d a r k D  - Dark.  50 6o -  d  80 20 20 -  -  MD  in  30 20  D  r  tone  -  -  -  g  e  g r o w t h  trees  of  1  a  M  ML Y o u n g;  Percent  c  s  o  w  class  -  h  t  20 70  -  _  -  -  -  -  -  -  - 58 -  Western r e d cedar always appears w i t h l i g h t e r tone t h a n t h a t of Douglas f i r o r w e s t e r n hemlock, due t o i t s t h i n n e r crown and b i g g e r leaves.  T h i s l i g h t e r tone i n most o f t h e cases i s s u f f i c i e n t t o  s e p a r a t e i t from the two o t h e r s p e c i e s .  C e r t a i n l y , i n s p e c i e s i d e n t i f i c a t i o n , tone p l a y s an i m p o r t a n t role.  When  due a l l o w a n c e s a r e made, p h o t o g r a p h i c tone i s a v a l u a b l e  and n e c e s s a r y i d e n t i f i c a t i o n f a c t o r , p a r t i c u l a r l y when i t i s used i n c o m b i n a t i o n w i t h crown shape, t e x t u r e , shadow p a t t e r n , and of  the p a r t i c u l a r s p e c i e s .  association  T h i s i s e s p e c i a l l y t r u e when l a r g e  homogeneous s t a n d s are r e p r e s e n t e d on a p i c t u r e .  On l a r g e s c a l e photos  where the d e t a i l s are more o b s c u r e d the tone becomes e x t r e m e l y i m p o r t a n t . O b v i o u s l y , tone has a g r e a t v a l u e i n g e n e r a l p h o t o - i n t e r p r e t a t i o n and s p e c i e s i d e n t i f i c a t i o n , b u t i t i s s t r o n g l y emphasized t h a t i t s h o u l d n o t form the s o l e b a s i s o f our  judgments.  VALUE OF TEXTURE 1.  The importance o f t e x t u r e t o the f o r e s t i n t e r p r e t e r . The t e x t u r e i s the f r e q u e n c y o f tone change w i t h i n the image.  Its  components a r e s i z e , shape, tone and d i s t r i b u t i o n o f u n i t f e a t u r e s  a c r o s s the image. or  I t i s d e s c r i b e d i n terms such as smoothness,  fineness  roughness. The r o l e p l a y e d b y t e x t u r e i s v e r y i m p o r t a n t I n f o r e s t type  mapping.  F o r example, w a t e r w i t h a f l a t s u r f a c e on a calm day w i l l  - 59 appear w i t h a smooth t e x t u r e . *  F u l l y stocked  young s t a n d s , becuase o f  t h e i r s i m i l a r crown s i z e and s m a l l s i z e o f image d e t a i l s , w i l l show as a f i n e l y t e x t u r e d p o r t i o n o f a photograph. many l a r g e r d e t a i l s , w i l l appear 2.  O l d growth, w h i c h has  coarse.  Factors i n f l u e n c i n g texture. Components o f t e x t u r e v a r y w i d e l y i n s i z e .  I f the  components a r e r e l a t i v e l y s m a l l , t e x t u r e w i l l appear f i n e .  When  f i n e n e s s i s reduced t o t h e p o i n t where t h e d e t a i l s a r e so minute t h a t t h e y a r e n o t d i s c e r n i b l e any more, t h e e f f e c t i s smooth t e x t u r e .  With  l a r g e r d e t a i l s , r e f l e c t i n g more l i g h t t h a n s m a l l e r , t h e minute changes i n tone w i l l be more f r e q u e n t  and c o n s e q u e n t l y t h e t e x t u r e w i l l appear  rough o r c o a r s e . The  images o f f o r e s t stands and o t h e r o b j e c t s can be used t o  i l l u s t r a t e the classes o f t e x t u r e . s t a n d has a f i n e t e x t u r e .  The image o f a v e r y young t i m b e r  The component t r e e s o f such a stand a r e so  s m a l l t h a t l i g h t r e f l e c t e d b y each t r e e i s n o t v i s i b l e on p h o t o g r a p h s . A c o m b i n a t i o n o f many such s m a l l stand components l o c a t e d s i d e b y s i d e , produces a f i n e t e x t u r e . Mature t i m b e r s t a n d s , on t h e o t h e r hand, have l a r g e components, which i n c l u d e : frequent  t h i c k b r a n c h e s o f t h e t r e e s , i r r e g u l a r crown shapes, and  openings i n crown canopy, a l l o f w h i c h a r e l a r g e enough f o r  p a r t s o f t h e stand t o be r e g i s t e r e d on f i l m as i n d i v i d u a l images, t h e r e b y causing  *  coarse t e x t u r e .  I t m i g h t be w e l l t o remember t h a t t h e word " t e x t u r a " o r i g i n a l l y comes f r o m t h e L a t i n v e r b " t o weave".  - 6o -  E v e r y component o f such a s t a n d i s l a r g e enough t o r e f l e c t enough l i g h t t o t h e camera t o be r e g i s t e r e d on l i g h t , s e n s i t i v e m a t e r i a l s o l e l y as an image o f an o b j e c t .  I n s u b j e c t s such as a l a w n , a f i e l d  o r v e r y young t r e e s ,  d e t a i l s o f such o b j e c t s a r e so s m a l l o r " f i n e " on o r d i n a r y photographs t h a t the f i l m cannot r e p r o d u c e any o f t h e minute d e t a i l s .  The  t e x t u r e o f an image may be c o n t r o l l e d b y t h e s i z e o f  g r a i n s i n t h e e m u l s i o n on l i g h t , s e n s i t i v e p h o t o g r a p h i c m a t e r i a l .  The  s m a l l e r t h e g r a i n s i n e m u l s i o n a r e , t h e more s e n s i t i v e i s t h e f i l m , t h e more d e t a i l s o f an image w i l l be r e g i s t e r e d , and t h e c o a r s e r t h e t e x t u r e w i l l be.  G e n e r a l l y , where the a l t e r a t i o n o f l i g h t and d a r k tones i s f r e q u e n t , t h e t e x t u r e on photographs r e g i s t e r s rough and c o a r s e . 3.  The t e x t u r e o f i n d i v i d u a l t r e e crowns. The  recognized.  t e x t u r e p a t t e r n formed b y i n d i v i d u a l t r e e crowns can be T e x t u r e o f t r e e crowns on photographs can be d e s c r i b e d as  the arrangement o f t h e h i g h l i g h t s and shadows and t h e r e l a t i v e amounts o f each.  A f i f t y - f i f t y d i v i s i o n o f b l a c k s and w h i t e s  s m a l l u n i t s produces a v e r y f i n e t e x t u r e .  i n extremely  G e n e r a l l y t h e l a r g e r and  more i r r e g u l a r t h e u n i t s o f b l a c k and w h i t e a r e , t h e c o a r s e r i s t h e texture.  The  t e x t u r e o f a t r e e i s t h e sum t o t a l o f a l l f a c t o r s t h a t  cause t e x t u r e , such as c o l o u r , shape, age, s p a c i n g between t h e branches  - 61 -  and w h o r l s ,  q u a l i t y o f f o l i a g e and g e n e r a l d e n s i t y o f t h e crown.  Colour. The  c o l o u r o f a t r e e i s an i n d i r e c t f a c t o r o f t r e e - t e x t u r e ,  because as such i t can be e i t h e r dark o r l i g h t i n t o n e , due t o t h e c o l o u r and n a t u r e  o f s u r f a c e , e t c . , o f p l a n t s b e i n g photographed.  Trees a r e u s u a l l y l i g h t e r i n c o l o u r i n t h e s p r i n g t i m e . Shape. Shape i s an i m p o r t a n t crowns.  f a c t o r i n texture of i n d i v i d u a l tree  On s p i k e d and i r r e g u l a r crowns t h e l o c a t i o n o f b r a n c h e s i s  always v i s i b l e u n l e s s t h e s c a l e i s v e r y s m a l l .  The r e g i s t r a t i o n o f  i n d i v i d u a l branches on t h e f i l m makes t h e t e x t u r e  The  coarse.  s i t u a t i o n i s much d i f f e r e n t i n t h e case o f t r e e s w i t h a  r e g u l a r , rounded shape.  The b r a n c h e s on such t r e e s a r e l o c a t e d on t h e  t r u n k i n a p a t t e r n t o o b t a i n more s u n l i g h t , f o r w h i c h t h e rounded shape has proved t o be t h e optimum form. branches a r e o c c u p i e d  Spaces between t h e s e c o n d a r y  w i t h dense l e a f f o l i a g e .  The t e x t u r e o f such  t r e e s w i l l always be f i n e , u n l e s s t h e l e a v e s a r e bunchy, as i n oaks, w h i c h appear w i t h coarse  texture.  Size. A group o f l a r g e o b j e c t s r e f l e c t s more l i g h t t o t h e camera, c a u s i n g more i r r e g u l a r b l a c k and w h i t e u n i t s , t h a n a group o f s m a l l objects.  The t e x t u r e o f l a r g e t r e e - c r o w n o b j e c t s w i l l appear r o u g h e r  than t h a t o f s m a l l o b j e c t s .  - 62 Age. I t i s w e l l known i n f o r e s t r y that the crown shape of a tree changes w i t h age. Since the e f f e c t of age involves the change of spacing between the branches and whorls themselves, these f a c t o r s w i l l be discussed here. From the viewpoint of texture, the e f f e c t of age i s most important when the tree approaches maturity, because t h i s i s the period when i t s crown becomes i r r e g u l a r .  By slackening of the v i t a l processes  of the t r e e , some of the whorls having accomplished t h e i r f u n c t i o n become useless to the tree and d i e . I r r e g u l a r i t y i s e a s i l y v i s i b l e on mature western hemlock and even more d e f i n i t e on mature Douglas f i r , where branches may form patches on the trunk, w i t h large gaps between them ( F i g . 2 j and Appendix I n.o.). extremely coarse on photos.  The texture of such trees w i l l appear  In the case of mature western red cedar,  where the whorls are not d i s t i n c t , the e f f e c t of maturity shows up i n e n l a r g i n g of distances between the branches and i n s i z e of the branches w i t h dead top, s t i c k i n g up l i k e a sharp s t i c k (Appendix I I I f ) . These n a t u r a l f a c t o r s cause i r r e g u l a r i t i e s i n crown and coarser texture on photographs, independently of the kind of f i l m , paper and f i n i s h i n g . I t i s worthwhile to mention also that the changes i n crown shape are d i f f e r e n t i n various parts of the crown.  The lowest p o r t i o n  of the crown u s u a l l y changes i n a much d i f f e r e n t way than the middle p o r t i o n . The sharpest d i f f e r e n c e s i n change are between the upper and lower portions of the crown.  Because of these above-mentioned  reasons,  a thorough examination of changes i n shape cannot be l i m i t e d j u s t t o  - 63 -  one p o r t i o n o f the crown, b u t must be extended t o the whole, i s p a r t i c u l a r l y important views.  i t  when the t r e e s are examined f r o m d i f f e r e n t  I f the t r e e i s examined from a v e r t i c a l v i e w , the changes i n  a l l t h r e e p o r t i o n s o f the crown are e q u a l l y i m p o r t a n t  i n c o n t r o l of  texture.  Q u a l i t y o f f o l i a g e and  g e n e r a l d e n s i t y o f the  crown.  I t can be s t a t e d g e n e r a l l y t h a t the denser the crown, the f i n e r i t s t e x t u r e w i l l appear on a p h o t o g r a p h .  The  general  o f the crown i s i n f l u e n c e d by the q u a l i t y o f the f o l i a g e . would seem t h a t c o n i f e r s , h a v i n g denser f o l i a g e and  density At f i r s t i t  smaller leaves  than  deciduous t r e e s , would have f i n e r t e x t u r e on photos t h a n deciduous t r e e s w i t h b r o a d l e a v e s , w h i c h may individually.  The  r e f l e c t enough l i g h t t o be r e g i s t e r e d  t e x t u r e i n the case o f c o n i f e r s w i l l be  m a i n l y by s i z e o f the branches and  determined  j u s t s e c o n d a r i l y by the s i z e o f the  l e a v e s and d e n s i t y o f f o l i a g e , because the l e a v e s are i n any case so s m a l l t h a t t h e y cannot be r e s o l v e d a t a l l .  S i n c e the branches are  r e l a t i v e l y l a r g e r o b j e c t s t h a n the l e a v e s , the t e x t u r e o f c o n i f e r s w i l l be  coarser.  I n the case o f deciduous s p e c i e s , on the o t h e r hand, d e s p i t e t h e i r b i g g e r l e a v e s , the t e x t u r e w i l l be f i n e r because the b r o a d  leaves  o f t h e s e s p e c i e s are h i d i n g the more o r l e s s t h i c k b r a n c h e s o f the t r e e , and the t e x t u r e i s d e t e r m i n e d by l e a v e s .  The  amount o f l i g h t r e f l e c t e d  t o the camera-by b r o a d l e a v e s i s u n d o u b t e d l y l a r g e r t h a n t h a t by needle leaves of c o n i f e r s .  However, t h e s e cannot be r e s o l v e d  individ-  u a l l y , because most o f the r e f l e c t e d l i g h t i s i n d i r e c t because o f  - 6h -  the l a r g e v a r i e t i e s o f a n g l e s w i t h w h i c h t h e l e a v e s hang on the t w i g s , and  t h e s i z e o f t h e l e a v e s w h i c h a r e n o t l a r g e enough t o be r e s o l v e d  even on l a r g e s c a l e p h o t o s . h.  T e x t u r e o f stands o f t r e e s . The  d i f f e r e n c e i n t e x t u r e o f a mixed stand i s v e r y h e l p f u l  i n r e c o g n i t i o n o f t h e s p e c i e s f o r m i n g t h e stand i t s e l f .  Single  trees  may have a p e c u l i a r crown t e x t u r e , b u t t h e y a r e e x t r e m e l y d i f f i c u l t t o recognize  i n mixed s t a n d s , u n l e s s t h e s c a l e i s l a r g e . The  t e x t u r e o f a stand i s i n f l u e n c e d b y a l m o s t t h e same  f a c t o r s as t h e t e x t u r e o f i n d i v i d u a l t r e e s :  shape, age ( i n c l u d i n g  s i z e o f t r e e s and s p a c i n g between t r e e s w i t h i n the s t a n d ) , and f o l i a g e . Shape. The texture.  shapes o f crowns have a g r e a t i n f l u e n c e on t h e stand  Since the a e r i a l p i c t u r e s are studied i n stereoscopic  the crown shape i s more o r l e s s a p p a r e n t .  pairs  Most o f t h e c o n i f e r s ,  e s p e c i a l l y t h e s p r u c e s and f i r s , have c o n i c a l crowns, w h i c h a r e u s u a l l y easy t o r e c o g n i z e ,  as such.  Trees w i t h crown shapes n a r r o w i n g upward  f o r m a dense stand  canopy i n l o w e r p o r t i o n s o f t h e crown, b u t between  the upper p o r t i o n o f t h e i r crowns, t h e space i s more extended. t e x t u r e o f such s t a n d s may appear  The  coarse.  Deciduous t r e e s , on t h e o t h e r hand, u s u a l l y have rounded crown shapes.  The space u t i l i z a t i o n o f round o b j e c t s i s always b e t t e r  t h a n t h a t o f c o n i c a l , t h e r e f o r e t h e r e w i l l be l e s s space u t i l i z e d  - 65 (shadow spaces) hy a canopy of round t r e e s t h a n by one of t r e e s h a v i n g a c o n i c a l shape.  Despite  t h e f a c t t h a t the. c o n i f e r s f o r m a denser  stand  t h a n d e c i d u o u s t r e e s , t h e t e x t u r e of t h e l a t t e r w i l l be f i n e r . G e n e r a l l y t h e more compact t h e crowns a r e t h e more even t h e t e x t u r e w i l l be. Age. As has been mentioned b e f o r e , t h e e f f e c t of age as such i s t h e most i m p o r t a n t f a c t o r i n c o n t r o l l i n g t e x t u r e , n o t o n l y of t h e i n d i v i d u a l t r e e s , b u t a l s o of t h e s t a n d .  Throughout t h e s t a n d ' s l i f e , changes a r e  produced i n t h e s t a n d s t r u c t u r e i t s e l f .  The e f f e c t shows up f i r s t o f a l l  i n e n l a r g i n g of t h e whole t r e e as t h e major component of t h e s t a n d . B u l k y i r r e g u l a r crowns w i t h l a r g e b r a n c h e s a r e t h e b a s i c f a c t o r s i n change of t e x t u r e .  There i s , however, a n o t h e r f a c t o r w h i c h i s s t i l l  more i m p o r t a n t t h a n t h e s i z e of t h e t r e e s , f r o m t h e v i e w p o i n t stand t e x t u r e - - t h e  s p a c i n g between t r e e s t h e m s e l v e s .  of t h e  The s p a c i n g  of t h e  i n d i v i d u a l p l a n t s i s t h e c h i e f f a c t o r t h a t produces t e x t u r e o f a s t a n d on a p h o t o g r a p h . i n a f o r e s t stand.  The c o m p e t i t i o n  among t h e t r e e s r e s u l t s i n o v e r g r o w t h  The f a s t e r - g r o w i n g  t r e e s , over-growing the s m a l l e r ,  s l o w e r - g r o w i n g ones, k i l l t h e weaker i n d i v i d u a l s , c r e a t i n g an i n c r e a s e d growing space f o r each t r e e .  The r e m a i n i n g t r e e s are i n some cases so  widely  s c a t t e r e d t h a t t h e y appear on a e r i a l photographs as i n d i v i d u a l  trees.  Only some s o - c a l l e d h e a v i l y t i m b e r e d stands show up w i t h con-  tinuous  stand  texture.  G e n e r a l l y , t h e more i n t o l e r a n t t h e t r e e s a r e , t h e more s c a t t e r e d and more upon t h e crowns, and t h e l a r g e r and more i r r e g u l a r  - 66 -  the shadow p l a c e s a r e , t h e c o a r s e r t h e t e x t u r e of t h e s t a n d w i l l be. Foliage. Deciduous s t a n d s , h a v i n g denser f o l i a g e c o v e r i n g t h e l a r g e components of t h e t r e e s , w i l l appear on summer photos w i t h f i n e r t e x t u r e t h a n t h a t of c o n i f e r s . old  Most o f t h e stands o f d e c i d u o u s s p e c i e s i n t h e i r  age a r e n e v e r as i r r e g u l a r e i t h e r i n shape o r i n s p a c i n g as t h e  c o n i f e r s , which i s another c h i e f reason f o r t h e i r f i n e r stand t e x t u r e . The f i n e r t e x t u r e of t h e s e s t a n d s i s t h e second most i m p o r t a n t  factor  a f t e r tone i n d i f f e r e n t i a t i n g t h e two k i n d s o f s t a n d s . 5.  Measurement o f t e x t u r e : T e x t u r e i s v e r y commonly u s e d as a d i s t i n g u i s h i n g c h a r a c t e r i s t i c  i n r e c o g n i t i o n keys. considered,  When f i n e ' p a t t e r n s such as t e x t u r e s a r e b e i n g  i t i s w e l l t o remember t h a t t e x t i l e s might v e r y w e l l be u s e d  when s e e k i n g t o d e f i n e d i f f e r e n t t y p e s o f t e x t u r e and t o p l a c e them on some k i n d of b a s i s where t h e meaning would be c l e a r t o everyone.  The  use o f such a s c a l e w o u l d be a g r e a t h e l p i n hands of p h o t o - i n t e r p r e t e r s , because t h e t e x t u r e o f s p e c i e s , j u s t l i k e t h e t o n e , i s named by words i n keys.  I t o f t e n happens t h a t what i s a f i n e t e x t u r e t o one o b s e r v e r  not n e c e s s a r i l y be so r e c o g n i z e d by a second o b s e r v e r .  would  I n connection  w i t h t h i s t h e r e f o r e , a s e t of t e x t i l e s d i s t r i b u t e d by t h e C o t t o n - T e x t i l e I n s t i t u t e has been u s e d as a s t a n d a r d  so t h a t when any t e x t u r e i s  e n c o u n t e r e d , t h e r e i s a t e x t i l e w h i c h can be u s e d t o match i t . i s s a i d that c e r t a i n vegetation'resembles  *  When i t  " c h e n i l l e " * ( o r any o t h e r  " C h e n i l l e " i s a t u f t e d c o r d f o r embroidery.  - 67 -  f a b r i c ) , t h e t e x t u r e on the p h o t o g r a p h i s b e i n g r e f e r r e d t o a s t a n d a r d t e r m s e t up b y t h i s I n s t i t u t e ( O ' N e i l , 1953)Sandpaper as a n o t h e r i n s t a n c e w i l l g i v e a s o r t of t e x t u r e appearance on a p h o t o g r a p h .  Cottage cheese and many o t h e r t h i n g s a r e  suggested by d i f f e r e n t a u t h o r s as the s t a n d a r d s are not w e l l s t a n d a r d i z e d .  of t e x t u r e s , b u t  they  They have not been u s e d as a i d s i n p h o t o -  i n t e r p r e t a t i o n , w i t h the e x c e p t i o n o f sandpaper and the t e x t i l e .  There  are many d i f f e r e n t sandpapers w i t h d i f f e r e n t grades o f sands and i t i s p o s s i b l e t o f i n d among them t e x t u r e s c l o s e l y r e s e m b l i n g v e g e t a t i o n o r c u l t i v a t e d f i e l d s as shown on a e r i a l p h o t o g r a p h s . The use of t e x t i l e s and sandpaper f o r the s t a n d t e x t u r e measurements, however, has many weaknesses.  T e x t i l e s are made o f  e n t i r e l y d i f f e r e n t m a t e r i a l s t h a n p h o t o s , and sandpaper appears comp l e t e l y d i f f e r e n t t h a n t h e stands e a s i l y be a source  on p h o t o g r a p h s .  B o t h f a c t o r s may  o f m i s i n t e r p r e t a t i o n . They are a l s o i n c o n v e n i e n t t o  use, thus n e i t h e r of these  standards  i s u s e d i n a e r i a l photo i n t e r p r e t a t i o n .  C o l w e l l (1952) s u g g e s t e d c u t t i n g out a p a r t f r o m a photo a p p e a r i n g w i t h d i f f e r e n t t e x t u r e d f o r e s t stands and u s i n g t h i s a s a s t a n d a r d i z e d s c a l e f o r measurement o f s t a n d t e x t u r e ( F i g . 6 ) .  The s c a l e s  of t e x t u r e would not be named b y words, b u t numbered, and t h i s number would r e p r e s e n t t h e t e x t u r e of t h e  stand.  - 68 Figure 6.  Texture Scale.  In a d d i t i o n t o Colwell's suggestion the present w r i t e r would advise that i t may be u s e f u l also t o work out a s i m i l a r type of texture scale f o r each scale of photos that are most widely used i n the f i e l d of f o r e s t r y , because i t may  happen that the  stand  which i s represented by texture scale No. 10 would have a f i n e r texture on a smaller scale photograph, and could match w i t h the number of another f i n e r scale.  I t i s obvious that stands  represented on texture scale No. are not i n the same condition as stands represented by No. 10.  The use of such a texture scale would give us the  same scale of texture f o r a very young and very o l d stand on two d i f f e r e n t scales of photos.  Such a change would make the texture scale  a v a i l a b l e f o r wider a p p l i c a t i o n such as f o r measuring textures of i n d i v i d u a l tree crowns, e t c . , and c e r t a i n l y would give the true representation of the k.  stand.  Changes i n texture of Douglas f i r , western hemlock and western red  cedar caused by d i f f e r e n t scale of photos. During the examination of changes i n texture of d i f f e r e n t species on various scale of photos, i t has been found that d i f f e r e n c e s i n texture were caused not only by the p r e v i o u s l y described reasons, but by the scale a l s o , which was found t o be one of the most important  - 69 f a c t o r s i n c o n t r o l l i n g of t e x t u r e . The changes i n texture were studied on the same f i v e kinds of photos, discussed on page  15.  During the survey, 20 Douglas f i r , 20 western hemlock and 20 western red cedar trees were examined. were young growth and t e n , o l d growth.  Ten of each of these species  Instead of numbers on a texture  s c a l e , words have been used f o r the texture c l a s s i f i c a t i o n s such as Rough, Coarse, F i n e , e t c . , which represent numbers on the texture s c a l e , as f o l l o w s : 1-2  Fine (F)  3-k Medium f i n e 5-6  Medium (M)  7-8  Coarse (C) •  9-10  Rough (R)  (MF)  The r e s u l t s of the survey are given i n Tables 27,  28 and  29-  Examining Table 27 i t can be r e a l i z e d that changes i n texture of young Douglas f i r t r e e s are caused mainly by decrease of photo scale.  As the  scale of photos i s decreased, the texture i s changed from Rough (R) t o Fine ( F ) , and r e s p e c t i v e l y f o r o l d growth. The change i n texture of young western hemlock i s almost i d e n t i c a l t o young Douglas f i r .  A s l i g h t change may be observed from  the f i g u r e s . Douglas f i r trees appear w i t h f i n e r texture than that of western hemlock t r e e s . cases overlap,  Unfortunately, the ranges i n texture i n many  j u s t as t h e i r tone ranges overlap.  However, overlapping  -  TO  -  occurs l e s s often i n texture than i n tone i n these two species. Changes i n texture of young and o l d western red cedar t r e e s show up most d i s t i n c t l y .  These may be explained by d i f f e r e n t f o l i a g e  and d i f f e r e n t changes i n shape and crown structure of cedar i n comparison w i t h Douglas f i r and hemlock than that of the two previous species. Generally, as the photographic scale p r o g r e s s i v e l y diminishas, texture of a given object becomes p r o g r e s s i v e l y f i n e r and eventually disappears. Table ZJ. Changes i n texture of Douglas f i r on d i f f e r e n t scales of photographs. Photo scale  Tex  ' R  t u r e  C  s c a 1 e MF  M  F  Percent of trees i n texture c l a s s Y 330 f t / i n . 729 1,200 1,500 2,400 "  TO  40 40 -  -  0  .u ;n g  10 30 30 40 10  -  w t h _  -  20 60  -  -  10 10 10  g r o w t h 20  -  0  20 30 20 30 20 0 1 d  1,200 f t / i n . 1,500 2,400 "  g r  -  80 20  -  _  80 100  - 71 T a b l e 28. Changes i n t e x t u r e o f w e s t e r n hemlock on d i f f e r e n t of p h o t o g r a p h s . s c a 1 e  T e X t u r e  Photo S CQ-ls R  C  scales  M  F  MF  P e r c e n t of t r e e s i n t e x t u r e c l a s s Y o u n g  6o 50 -  330 f t / i n . 720 1,200 1,500 2,400 ii  1!  It  1!  20 30 20 30  20 20 50 20 20  -  0 Id 6o 50 -  330 f t / i n . n 720 1,200 1,500 2,400 it  M  g r o w t h -  -  30 50 30  50  g r o w t h  10 20 20 80 -  30 30 70 10 -  _  _  10 10 10  90  T a b l e 29. Changes i n t e x t u r e of w e s t e r n r e d cedar on d i f f e r e n t s c a l e s of photographs. T e x  Photo scale R  C  M  Y o u  11 ti  11  11  -  n g  11  11 11  MF  4o 30 -  g r  0  F  w t h  -  60 20 -  30 70 30 10  80 20 20 0 1 a  330 f t / i n . n 720 1,200 1,500 2,400  s c a 1 e  P e r c e n t of t r e e s i n t e x t u r e c l a s s  •  330 f t / i n . 720 1,200 1,500 2,400  t u r e  30 50 -  g r  0  30 30 60 -  '  10 10 50 90  w t h _  _  4o 20 70 10  20 30 90  - 72 -  VALUE OF FILM AND FILTERS Films F i l m c o n s i s t s of two p a r t s ; the f i l m base or support, and a l i g h t , s e n s i t i v e l a y e r , c a l l e d the emulsion. two p a r t s :  the l i g h t , s e n s i t i v e s i l v e r compound c a l l e d g r a i n s , and a  g e l a t i n base. film.  The emulsion c o n s i s t s of  The smaller the g r a i n s , the greater the s e n s i t i v i t y of the  The greater i n t e n s i t y of exposure by l i g h t reaching the c r y s t a l s ,  the darker w i l l be the p o r t i o n of the f i l m .  S i l v e r c r y s t a l s which are  not struck by l i g h t remain undevelopable and w i l l be transparent a f t e r processing. light.  The degree of darkening i s dependent upon the density of  The higher the d e n s i t y , the darker the f i l m . There are two types of f i l m s used i n f o r e s t photogrammetry,  black and white and colour f i l m .  Because of t h e i r expense and weak  s e n s i t i v i t y , colour f i l m s are not used i n t e n s i v e l y , although  species  i d e n t i f i c a t i o n might be made w i t h a higher degree of accuracy than on black and white f i l m s .  The s e n s i t i v i t y of black and white f i l m s i s  d i f f e r e n t f o r d i f f e r e n t colour parts of the v i s i b l e spectrum. v i s i b l e colour spectrum c o n s i s t s of the f o l l o w i n g colours: Violet  kOO - kh6 m i l l i m i c r o n  Blue  kk6 - 500  "  Green  500 - 578  "  Yellow  578 - 592  Orange  592 - 620  Red  620 - 700  "  The  - 73 The f o r e s t p l a n t s r e f l e c t the green colour (500-578 m i l l i m i c r o n ) and those colours which are over the v i s i b l e spectrum.  According t o t h e i r  s e n s i t i v i t y , there are three types of black and white f i l m s :  ortho-  chromatic, panchromatic and i n f r a - r e d . 1.  Orthochromatic  film.  Orthochromatic f i l m i s designed t o record tone values corresponding t o tones of nature.  I n p r a c t i c e i t i s used t o designate a  f i l m s e n s i t i v e t o blue and green, but not t o r e d l i g h t .  The f i l m i s  s e n s i t i v e t o l i g h t s w i t h a wave l e n g t h of 560 m i l l i m i c r o n s ( F i g . JA) , w i t h l i m i t s of s e n s i t i v i t y at klO - 590 m i l l i m i c r o n s .  Since the most  f o r e s t d e t a i l s are green i n colour, orthochromatic f i l m s may be very u s e f u l i n tree species i d e n t i f i c a t i o n w i t h i n a s p e c i a l circumstance. Despite t h i s , orthochromatic f i l m s are not used widely i n f o r e s t r y i n comparison t o panchromatic or i n f r a - r e d f i l m , therefore they are discussed only b r i e f l y . 2.  Panchromatic  a.  Sensitivity  film. and use of the f i l m .  The panchromatic f i l m s have been used i n photogrammetry only since 1939-  They are s e n s i t i v e t o almost a l l colours of the v i s i b l e  spectrum from wavelength 415-665 m i l l i m i c r o n s ( F i g . 7B), i n c l u d i n g orange and r e d i n a d d i t i o n t o those colours recorded on orthochromatic film.  This kind of f i l m produces a p i c t u r e i n black and white which  appears normal t o human eyes.  The human eye d i s t i n g u i s h e s one colour  from another, p a r t l y because some colours are b r i g h t e r than others, some present more c o n t r a s t , some may be i l l u m i n a t e d more than others, and some d i f f e r i n degree of s a t u r a t i o n .  Various photographic f i l m s  react somewhat s i m i l a r l y i n being not equally s e n s i t i v e t o a l l colours.  To f o l l o w page 73  A  Sensitivity  curve of orthochromatic  film  a»  to  4x10"  5  cms  5  B  6  Wave Length (cm)  Sensitivity curve of panchromatic  film  CO  c 0  CO  4xl0"5 cms  C  5  6  Wave Length (cm)  Sensitivity curve of i n f r a - r e d  film  c CD  CO  4 x l 0 " cms 5  Fig- 7  5>6  Wave Length (cm)  7  Sensitivity curves of various types of film  8  - Ik -  The panchromatic f i l m comes as near as p o s s i b l e t o responding t o a l l colours that can be seen by human eyes.  I t i s used i n a l l black and  white photography when correct tone rendering i s desired. Most of the f o r e s t a e r i a l photographs are made w i t h panchromatic film.  The f i l m contains smaller grains and therefore i s more s e n s i t i v e  than orthochromatic.  I t s s e n s i t i v i t y i s about twice as f a s t as that of  i n f r a - r e d f i l m s (Schulte, 1951)-  The maximum of i t s s e n s i t i v i t y curve  i s at 635 m i l l i m i c r o n s , which shows that i t i s very s e n s i t i v e t o red light.  I t s higher s e n s i t i v i t y permits shorter exposures f o r the longer  penetrating red wave lengths at high a l t i t u d e s .  Advantage of  panchromatic f i l m s w i t h respect t o i l l u m i n a t i o n i s i t s a b i l i t y t o use r e f l e c t e d blue sky l i g h t .  The haze, however, i s the greatest disadvantage  i n the use of panchromatic f i l m s .  This d e f i n i t e l y l i m i t s the time when  panchromatic f i l m can be used. b.  Tone and texture of vegetation on panchromatic f i l m s . The photo-interpreter r e l i e s t o some extent on the tone when  r e c o g n i t i o n of species i s required.  The eye can detect tone d i f f e r e n c e s  of no l e s s than two percent on panchromatic f i l m s , but a c t u a l l y four percent i s more p r a c t i c a l i n recognizing trees (See page 50).  During  the summer, the leaves have more shades of green, varying from l i g h t t o dark green, s i l v e r y , w h i t i s h , y e l l o w i s h , or o l i v e green.  The  s e n s i t i v i t y of panchromatic f i l m t o the very c l o s e l y r e l a t e d wave lengths of these shades i s unfortunately not very s e l e c t i v e .  The shades of  green f o r a given species are rather constant, but w i t h j u s t enough v a r i a t i o n t o make the a p p l i c a t i o n of tone d i f f i c u l t as a r e l i a b l e  - 75 -  f a c t o r i n species i d e n t i f i c a t i o n .  However, the over-exposure of hard-  woods and under-exposure of c o n i f e r s i s advantageous on panchromatic f i l m s , whereas i t i s disadvantageous on i n f r a - r e d f i l m s , as i t causes l o s s of photographic d e t a i l s .  Differences i n exposure may produce t o n a l  contrasts which r e a d i l y permit the photo separation of hardwoods from conifers.  Generally, panchromatic f i l m gives b e t t e r d e t a i l f o r low  shrubby areas, grasses, rocks, s o i l s , e t c . , and the density of a f o r e s t a l s o can be estimated more a c c u r a t e l y , than on the two above mentioned ones. The texture of an object on a panchromatic f i l m i s more d i s t i n c t i n some respects than that given by i n f r a - r e d or orthochromatic photographs.  The d i f f e r e n c e s are due t o the f a c t that panchromatic f i l m  i s not as contrasting as the forementioned ones. more d e t a i l ;  Panchromatic f i l m s give  the l a r g e r the scale of the photographs, the more the  d e t a i l s can be resolved, which i s a great advantage i n f o r e s t species interpretation. 3. a.  Infra-red f i l m S e n s i t i v i t y and use of the f i l m . Before evaluating a e r i a l i n f r a - r e d photography f o r the  i d e n t i f i c a t i o n of p l a n t s , some fundamental points should be considered, regarding the nature of i n f r a - r e d photography.  I n f r a - r e d f i l m records  r a d i a t i o n s which are beyond the v i s i b l e spectrum.  The average human  eye i s s e n s i t i v e , as i t has been mentioned above, t o wave lengths i n the range from kOO t o 700 m i l l i m i c r o n s , which form the v i s i b l e spectrum. The Commercial type of i n f r a r e d f i l m used i n a e r i a l photography i s  - 76 -  s e n s i t i z e d between 4l9 (Fig.  70).  - 510 m i l l i m i c r o n and 668  - 850 m i l l i m i c r o n  I n f r a - r e d wave lengths are not v i s i b l e t o the human eye,  i t therefore•cannot  and  be shown by i n s p e c t i o n how a given object w i l l be  recorded on i n f r a - r e d photographs. Techniques of using i n f r a - r e d f i l m s do not d i f f e r from that of ordinary panchromatic and orthochromatic  films.  m o d i f i c a t i o n s , however, must be s a t i s f i e d . lens must be used.  Two  important  The f i r s t i s that a corrected  The lenses i n cameras using panchromatic f i l m are  corrected so that wave-lengths i n the v i o l e t and yellow are both i n focus i n the same plane.  I f the camera i s not equipped w i t h a s p e c i a l l y  corrected lens f o r use w i t h i n f r a - r e d f i l m , an acceptable  practical  c o r r e c t i o n can be made by changing the f o c a l length about one (Spurr, 1949).  percent  The second m o d i f i c a t i o n i s the use of various f i l t e r s i f  only i n f r a - r e d r a d i a t i o n s are required t o be recorded, as i n f r a - r e d f i l m i s s e n s i t i v e not only t o i n f r a - r e d but a l s o t o v i o l e t , u l t r a v i o l e t blue wave-lengths.  and  In order t o insure the transmission of only i n f r a -  red waves through lenses, f i l t e r s are used t o absorb the undesirable v i s i b l e and n o n - v i s i b l e l i g h t s ( C l a r k , 19^7). One of the chief d i f f i c u l t i e s i n obtaining good a e r i a l photographs by means of colour or other black and white photography 'is the haze i n the atmosphere. lengths penetrate t h i n haze.  I t has been found that i n f r a - r e d waveI n f r a - r e d photographs can be taken  s a t i s f a c t o r i l y when the haze i s too t h i c k f o r panchromatic photography. Dense haze or f o g , however, cannot be penetrated even by i n f r a - r e d photography.  Harrison (19^-6 ) found that i f the haze i s so dense that  - 77 the v i s u a l range i s l e s s than one-third  of a m i l e , no  satisfactory  r e s u l t s can be expected beyond the l i m i t of i n f r a - r e d photography. Hulburt (1935) made a series of photographs t o determine whether objects could be photographed through fog by i n f r a - r e d from a greater  distance.  His r e s u l t s showed that i t i s d i f f i c u l t to estimate v i s u a l l y the distance which i n f r a - r e d w i l l penetrate.  Generally the b e t t e r the v i s u a l s i g h t ,  the b e t t e r the extent t o which penetration can be increased by the use  of  infra-red f i l m . The  chief disadvantage of i n f r a - r e d f i l m i s that when the  trees  of a f o r e s t stand are i n the shadow of a h i l l or i n a dense stand, the shadow pattern and the crown form of i n d i v i d u a l trees cannot be seen. The most important use of t h i s f i l m i s i n s o i l mapping.  Since  water absorbs i n f r a - r e d l i g h t waves, i t appears b l a c k on i n f r a - r e d f i l m s . The more water i n the s o i l , the darker w i l l be i t s tone on a photograph. Because water g r e a t l y influences the q u a l i t y of s o i l s , i n f r a - r e d f i l m s are very u s e f u l i n s o i l mapping. b.  Tone and texture of vegetation. One  of the most important differences between i n f r a - r e d  and  other black and white photography i s that the c h l o r o p h y l l , the p r i n c i p a l colour substance i n the f o l i a g e of tree species, has a very high transparency i n i n f r a - r e d and that i n f r a - r e d r a d i a t i o n i s therefore r e f l e c t e d by the l e a f t i s s u e s instead of being absorbed by the (Clark, 1947).  chlorophyll  I n f r a - r e d r a d i a t i o n s r e f l e c t e d by the l e a f t i s s u e s  r e g i s t e r s i n l i g h t tones t h e r e f o r e , and f o l i a g e s which absorb i n f r a - r e d  - 78 -  l i g h t w i l l r e g i s t e r i n dark tone on i n f r a - r e d photographs.  Generally, c o n i f e r s  r e g i s t e r i n dark tones and deciduous trees r e g i s t e r i n l i g h t tones. C e r t a i n types of vegetation r e f l e c t i n f r a - r e d l i g h t b e t t e r than others.  Ives (1939) i n v e s t i g a t i n g the use of i n f r a - r e d f i l m s f o r  e c o l o g i c a l surveys found that healthy grasses and immature trees were b e t t e r r e f l e c t o r s than drying grasses and mature t r e e s .  An o l d tree  appears darker on i n f r a - r e d f i l m than a younger, assuming that they are of the same species, because i t has a more i r r e g u l a r crown which absorbs more i n f r a - r e d l i g h t . Many f i l t e r s were used t o experiment w i t h i n f r a - r e d f i l m t o improve the tones by decreasing the contrast.  I t has been found that most  t o n a l v a r i a t i o n s between t r e e s and other vegetation can be detected w i t h i n f r a - r e d f i l m s , i f they are used w i t h minus blue f i l t e r .  As a r e s u l t , the  contrasts are softened so that thh deciduous t r e e s , instead of appearing very l i g h t , d i s p l a y s l i g h t l y d i f f e r i n g tones of l i g h t grey.  The c o n i f e r s ,  instead of appearing black, d i s p l a y varying tones of dark grey t o black. Sonley (19^6) reported that i n h i s Canadian t e s t s i n f r a - r e d w i t h a minus blue f i l t e r produced more contrast than the red f i l t e r .  T h i s i s contrary  to the r e s u l t s of other researchers i n the U.S. and a l s o contrary t o what he expected.  At present, most of the i n f r a - r e d f i l m s are used together  w i t h minus blue f i l t e r . The tone of Douglas f i r , western hemlock and western red cedar appears on i n f r a - r e d photos w i t h l e s s v a r i a t i o n than on panchromatic photos, which i s due t o the nature of the f i l m and minus blue f i l t e r .  - 79 -  Changes i n tone of Douglas f i r and western hemlock are v a r y i n g between Medium and Medium L i g h t , whereas that of western red cedar v a r i e s between Medium and L i g h t ranges of the tone s c a l e .  Unfortunately, thorough study  i n changes of tone of these species could not be made, because of l a c k of i n f r a - r e d photographs. h.  Colour f i l m s .  a.  S e n s i t i v i t y and use of the f i l m . I n a l l of the f i e l d s of f o r e s t photogrammetry,  conventional  black and white photography has been a p p l i e d w i t h a f u l l scale. A p p l i c a t i o n of a e r i a l colour photography, however, i s s t i l l very l i m i t e d . Although a e r i a l colour photography has proved by i t s unique q u a l i t i e s t o be of superior value i n such f i e l d s as photo i n t e r p r e t a t i o n , reconnaissance, and management planning, i t i s not used as e x t e n s i v e l y as the black and white. Since World War I I , the q u a l i t y of a e r i a l colour f i l m s has been improved constantly i n i t s colour f i d e l i t y , colour balance, and fineness of grains.  sensitivity  Many new colour f i l m s have a l s o been developed.  The most common colour f i l m s used i n the United States and Canada are Kodak Ektachrome Aero, Kodak Ektachrome Camouflage Detection, Kodak Aero E k t a c o l o r , Anscochrome and Super Anscochrome.  European colour f i l m s used  i n a e r i a l photography are: Agfacolor, Gevacolor and F e r r a n i c o l o r . Colour f i l m s are s e n s i t i z e d t o wave lengths not only i n the 400-500 m i l l i m i c r o n band of the v i s i b l e spectrum, but a l s o t o l a r g e r wave lengths.  They reproduce a l l the colours more or l e s s f a i t h f u l l y as  - 80 -  t h e eye  sees them.  white f i l m s .  The  The  c o l o u r f i l m l a c k s t h e g r a i n s o f t h e "black  and  absence o f s i l v e r p e r m i t s g r e a t e r m a g n i f i c a t i o n s w i t h -  out i n t e r f e r e n c e o f g r a i n . C o l o u r photography has i n h e r e n t advantages o v e r b l a c k and  white,  p a r t i c u l a r l y i n a p p l i c a t i o n s where p h o t o - i n t e r p r e t a t i o n i s dependent upon true colour rendition.  I n b l a c k and w h i t e photography, t h e  limitation  i n h e r e n t i n r e p r o d u c t i o n o f o n l y monochromatic gray t o n e s can be  only  p a r t l y overcome by s p e c i f i c f i l m and f i l t e r c o m b i n a t i o n s t h a t i n c r e a s e t o n a l c o n t r a s t between t r e e s p e c i e s . b.  Tone o f v e g e t a t i o n on c o l o u r photographs. C o l o u r photographs t e n d t o r e c o r d v e g e t a t i o n as i t n a t u r a l l y  appears. recorded  T h i s advantage i s v e r y i m p o r t a n t  when t h e d i f f e r e n t  on the photographs can be a s s o c i a t e d w i t h d i f f e r e n t  colours species.  I d e n t i f i c a t i o n o f t r e e s p e c i e s , f o r e s t and o t h e r v e g e t a t i o n t y p e s  based  upon c o l o u r d i f f e r e n c e s o f f e r g r e a t p o s s i b i l i t i e s on good q u a l i t y c o l o u r photos.  W i t h b l a c k and w h i t e photography, such d i s t i n c t i o n i s o f t e n ex-  ceedingly d i f f i c u l t .  Modern c o l o u r f i l m s are capable  o f r e n d e r i n g even  f a i n t hues, making t h e i d e n t i f i c a t i o n o f t r e e s p e c i e s more r e l i a b l e efficient.  U n f o r t u n a t e l y , t h e s e modern c o l o u r f i l m s are v e r y  and  expensive,  and t h e r e f o r e can h a r d l y be used i n p r a c t i c e e c o n o m i c a l l y .  Changes i n f o l i a g e r e f l e c t i v i t y w i t h seasons o f t h e y e a r be a d v a n t a g e o u s l y used f o r d i s t i n c t i o n between t r e e s p e c i e s .  can  Perhaps t h e  g r e a t e s t advantage o f c o l o u r photography l i e s i n i t s use f o r s p r i n g and autumn f o l i a g e .  However, as f o r any photography o f v e g e t a t i o n u n d e r g o i n g  - 81 -  seasonal changes, the time and place are u s u a l l y very l i m i t e d , e s p e c i a l l y when the uneven rates of colour change and the number of f a i r days f o r photography are considered. The disadvantages  of colour photography i n comparison t o black  and white may be pointed out as follows: i  Colour photography i s expensive.  Wear and Dilworth (1955) r e -  ported a 20$ higher d i r e c t cost f o r colour photography than f o r s i m i l a r black and white photography. ii  Black and white f i l m s can be manufactured w i t h both stable and uniform c h a r a c t e r i s t i c s . s t i l l f a r from uniform.  At present, colour f i l m s are  Colour balance and q u a l i t y are the  r e s u l t of a complex i n t e r a c t i o n between the three emulsions that d i f f e r s l i g h t l y from one l o t t o another.  V a r i a b i l i t y of  f i l m emulsions i s one of the main reasons why a e r i a l photo graphy has achieved varying degrees of success or f a i l u r e . Under and over exposures w i l l a f f e c t the colour balance and the q u a l i t y of colour photos considerably. iii  The problem of haze i s much greater f o r colour photography than f o r black and white.  Weather l i m i t a t i o n s are also greater,  and the chances of s a t i s f a c t o r y r e s u l t s are never too good. iv  Colour f i l m s are generally considered t o be much slower i n s e n s i t i v i t y than comparable black and white f i l m s , p a r t i c u l a r l y i f they are used w i t h c o r r e c t i n g  filters.  - 82 -  v  C o l o u r f i l m s a r e more s a t i s f a c t o r y i f t h e y a r e used as t r a n s parencies. cy  S p e c i a l equipment i s needed when c o l o u r t r a n s p a r e n -  i s s t u d i e d , w h i c h c r e a t e s problems i n f i e l d work.  A s t u d y o f changes o f t o n e i n Douglas f i r , w e s t e r n hemlock and w e s t e r n r e d cedar c o u l d n o t he made w i t h i n t h e frame o f t h i s work, because of l a c k o f c o l o u r p h o t o g r a p h s . Filters. F i l t e r s a r e a t r a n s p a r e n t m a t e r i a l used i n t h e o p t i c a l p a t h o f a camera l e n s t o absorb a c e r t a i n u n d e s i r e d p o r t i o n o f t h e spectrum and prevent i t s reaching the s e n s i t i z e d photographic f i l m . u a l l y used i n photogrammetry  F i l t e r s a r e us -  t o m i n i m i z e o r c u t o u t t h e b l u i s h haze gen-  e r a l l y p r e s e n t i n t h e atmosphere, o r t o a c c e n t u a t e t o n a l c o n t r a s t between d i f f e r e n t s p e c i e s and f o r e s t t y p e s .  G e n e r a l l y , t h e c h o i c e o f f i l t e r de -  pends upon t h e amount o f haze, t h e t y p e o f f i l m b e i n g used, and t h e de sired tone. the  The more b l u e l i g h t t h e f i l t e r c u t s o u t , t h e b e t t e r w i l l be  haze p e n e t r a t i o n .  Haze c o n s i s t s c h i e f l y o f smoke, vapour and d u s t .  To form a haze, t h e s e p a r t i c l e s must n o t exceed one m i c r o n i n d i a m e t e r ( C l a r k , 19^7)•  The e f f e c t o f haze i s t h a t i t s c a t t e r s t h e b l u e l i g h t  and t h e r e b y produces a b l u e - c o l o u r e d haze.  I n a e r i a l photography a t  10,000 f e e t , haze can be c o n s i d e r a b l e , even though an o b s e r v e r on t h e ground does not p e r c e i v e i t . Y e l l o w f i l t e r s a r e most commonly used i n f o r e s t w i t h o r t h o c h r o m a t i c , p a n c h r o m a t i c and i n f r a - r e d f i l m s .  photogrammetry  Other c o l o u r s o f  f i l t e r s such as green and medium r e d a r e a l s o used w i t h b l a c k and w h i t e  - 8  3  -  film. In order t o reduce the e f f e c t of b l u i s h haze i n forest a e r i a l photography, panchromatic f i l m s are u s u a l l y exposed through yellow f i l ters.  A l i g h t yellow f i l t e r , Wratten No. 3; cuts out most r a d i a t i o n  shorter than ^50 m i l l i c r o n s . us blue f i l t e r )  The medium yellow Wratten No. 12 (or min -  cuts out l i g h t shorter than 500 m i l l i m i c r o n s , and the red  Wratten 25 transmits l i g h t only longer than 58O m i l l i m i c r o n s . I n f r a - r e d f i l m s are also exposed through f i l t e r s . various f i l t e r s used with i n f r a - r e d f i l m s .  There are  The blue-green s e n s i t i v e por-  t i o n i s f i l t e r e d out with a medium red f i l t e r , Wratten No. 25.  A "deep"  red f i l t e r , Wratten No. 29, removes v i s i b l e r e d l i g h t below 680 m i l l i microns.  These f i l t e r s produce normal i n f r a - r e d photography. Modified i n f r a - r e d photography i s produced w i t h the use of a  l i g h t f i l t e r , which allows some blue-green l i g h t as w e l l as the r e d i n i n f r a - r e d r a d i a t i o n t o reach the f i l m , g i v i n g normal t o n a l v a r i a t i o n s and c u t t i n g down the sharp contrast.  On modified i n f r a - r e d photographs the  darkest and the l i g h t e s t trees can be r e g i s t e r e d with good d e t a i l s i n grey.  I t i s achieved u s u a l l y with medium yellow, Wratten No. 12 or min-  us blue f i l t e r .  Clark (19V7) S  a v e  a  l i s  t °f  s o m e  f i f t y f i l t e r s that can  be used with i n f r a - r e d f i l m . A e r i a l colour photography also requires c o r r e c t i n g  filters.  The main f u n c t i o n of a f i l t e r i s t o improve the colour balance by a f f o r d ing s e l e c t i v e c o n t r o l of the wave-length admitted t o s e n s i t i z e d emulsion layers.  Becking (1959) recommended the use of two types of  - Qk -  filters are  with aerial  c o l o u r f i l m s , H F - f i l t e r s and E F - f l i t e r s .  HF-filters  used f o r haze c o r r e c t i o n , e s p e c i a l l y i f t h e photographs a r e t a k e n  from h i g h a l t i t u d e , when t h e haze i n t e r f e r e n c e on t h e c o l o u r b a l a n c e i s very great.  An orange o r y e l l o w f i l t e r w i l l u s u a l l y compensate f o r t h e  predominance  o f b l u e c o l o u r t h a t r e s u l t s from haze.  The E F - f i l t e r s a r e  used t o compensate d i f f e r e n c e s i n c o l o u r b a l a n c e between f i l m l o t s .  The  proper E F - f i l t e r i s u s u a l l y s p e c i f i e d by t h e f i l m manufacturer. VALUE OF SEASON TO PHOTOGRAPHY The season o f photography c a n g r e a t l y a f f e c t t h e v a l u e o f photographs f o r f o r e s t r y p u r p o s e s , because o f t h e n a t u r e o f v a r i o u s t r e e species.  Deciduous  species l o s e t h e i r f o l i a g e during the winter time, there-  f o r e o n l y t h e c o n i f e r s can be s t u d i e d .  I n t h e s p r i n g and f a l l , t r e e  fol-  i a g e changes i n c o l o u r and t o n e , w h i l e i n summer t h e f o l i a g e has normal colour.  These f a c t o r s may determine t h e c h o i c e o f f i l m and f i l t e r com-  b i n a t i o n s used i n d i f f e r e n t  a.  S p r i n g and f a l l  seasons.  photography  The problems o f s p r i n g and f a l l photography a r e t h e same.  On  photographs t a k e n d u r i n g t h e s p r i n g o r f a l l , d e c i d u o u s t r e e s w i l l r e g i s t e r w i t h l i g h t t o n e and c o n i f e r o u s w i t h dark t o n e s .  F o l i a g e o f broad-  l e a f t r e e s i s l i g h t yellow-green, w h i l e f o l i a g e o f evergreen species i s dark green.  T h i s i m p o r t a n t f a c t h e l p s us t o s e p a r a t e b o t h o f them e i t h e r  i n pure o r i n mixed s t a n d s . There a r e , however, some g r e a t drawbacks a l s o i n photography f o r b o t h seasons.  The sun i s h i g h i n t h e s p r i n g months, t h e r e f o r e i t  - 85 -  r e d u c e s t h e shade o f i n d i v i d u a l t r e e s and t h u s d e c r e a s e s t h e use o f some d e t a i l s p r o d u c e d "by shade.  The number o f p h o t o g r a p h i c days i s s m a l l i n  b o t h seasons. " I f photographs a r e t a k e n t o o e a r l y i n t h e f a l l some o f t h e d e c i d u o u s may n o t have changed t h e i r c o l o u r and may be c o n f u s e d w i t h e v e r g r e e n . I f photographs are t a k e n t o o l a t e o t h e r s p e c i e s may have l o s t t h e i r l e a v e s and w i l l n o t be r e s o l v e d i n t h e photographs .. " ( S p u r r , 1948) <  S i m i l a r t r o u b l e s may o c c u r i n s p r i n g t i m e a l s o , because b r o a d l e a f s p e c i e s b e g i n t o "blossom a t d i f f e r e n t t i m e s .  The same s p e c i e s may  r e g i s t e r on t h e same p i c t u r e w i t h e n t i r e l y d i f f e r e n t t o n e s .  For spring  and f a l l photography, panchromatic f i l m s w i t h y e l l o w f i l t e r o r c o l o u r f i l m s a r e used.  Modified i n f r a - r e d technique w i l l also give  satisfactory  results. "b.  Summer photography Most f o r e s t photography i s c a r r i e d out d u r i n g t h e summer, when  f o l i a g e i s a t normal c o l o r a t i o n . The number o f f l y i n g days i s l a r g e r t h a n I n any o t h e r season and t h e p i c t u r e s c o n t a i n a maximum o f i n f o r mat i o n .  All  t y p e s o f f i l m and f i l t e r s a r e used i n summer, "but t h e most  common ones a r e p a n c h r o m a t i c f i l m s w i t h y e l l o w o r green f i l t e r s . f o r m e r g i v e a b e t t e r appearance and r e s o l u t i o n , and t h e l a t t e r sharp c o n t r a s t . success.  The  give  M o d i f i e d i n f r a - r e d f i l m s are used a l s o w i t h a great  Summer photographs w i t h p a n c h r o m a t i c f i l m s a r e o f t e n t a k e n a t  summertime t o g i v e an RF o f 1 : 10,000.  - 86 -  c.  W i n t e r photography. The  d i f f e r e n c e s between deciduous  and c o n i f e r o u s t r e e s a r e t h e  s h a r p e s t on p i c t u r e s made i n w i n t e r , t h e r e f o r e i t i s most o f t e n used i n s e p a r a t i o n o f deciduous  and e v e r g r e e n  stands.  The p o s i t i o n o f t h e sun  i s l o w i n t h e sky i n w i n t e r , t h e r e f o r e t h e shadows a r e l o n g , d i s t i n c t , and a r e a v a i l a b l e f o r a c c u r a t e h e i g h t d e t e r m i n a t i o n b y t h e shadow method. The g r e a t drawback o f p i c t u r e s t a k e n i n w i n t e r months i s t h a t t h e s p e c i e s i d e n t i f i c a t i o n o f deciduous and o t h e r deciduous  trees i s very d i f f i c u l t .  Where hardwoods  s p e c i e s a r e common, and have r e a l economic  t h e w i n t e r photography must be c o n s i d e r e d .  importance,  P i c t u r e s taken i n t h i s  seas-  on a r e most o f t e n used i n t o p o g r a p h i c mapping, because t h e t o p o g r a p h y and o t h e r d e t a i l s o f t h e a r e a can be seen w e l l t h r o u g h bare Orthochromatic,  b u t m a i n l y panchromatic  trees.  f i l m s , a r e used f o r  w i n t e r photography w i t h green o r minus b l u e f i l t e r , p r o d u c i n g a good t o n a l c o n t r a s t between s p e c i e s .  - 87 -  EVALUATION OF DIFFERENT PHOTO SCALES IN INTERPRETATION OF TREE SPECIES 1.  Advantages and disadvantages of various scales i n species r e c o g n i t i o n . The scale of photography imposes one of the most serious  l i m i t a t i o n s on the r e s u l t s to he obtained from any study.  There i s  no standard scale which w i l l s a t i s f y the many users of a e r i a l There i s one b a s i c f a c t only:  photography.  i t i s impossible to have both a l a r g e  area coverage and a large scale In the same single "9 x 9" p r i n t . Because of t h i s f a c t , a compromise i s necessary -- one must be adjusted or even s a c r i f i c e d at the expense of the other. A RF varying between 1 : 3,000 and 1 : 4,000 may  be  e x c e l l e n t f o r i d e n t i f i c a t i o n of minute d e t a i l s , such as the study of crown d e t a i l s of a t r e e , or any other small p a r t of an o b j e c t . But such a scale i s f a r too l a r g e f o r general f o r e s t r y purposes because the f o r e s t i n t e r p r e t a t i o n s , i n c l u d i n g species i d e n t i f i c a t i o n , are contingent on the study of a l l parts of an area and not only on the minute d e t a i l s and the r e l a t i o n e x i s t i n g between them.  Since large scale photos cover l e s s  area than smaller ones, the economic requirements are only accomplished with d i f f i c u l t y .  Hence there i s required a great number of p r i n t s f o r  area coverage, therefore the wide use of t h i s scale of photos f o r p r a c t i c a l study of f o r e s t stands and i t s r e l a t i o n to the t e r r a i n are precluded. Mechanical d i f f i c u l t i e s are of considerable importance.  Such items as  r e - c y c l e time of the camera, low a l t i t u d e , image motion, and shutter speed must be considered. The most important f a c t o r f o r i d e n t i f i c a t i o n of a tree on the l a r g e scale photos i s the texture ( l o c a t i o n and the arrangement of  - 88 -  the branches on the bole) rather than the tone or crown shape.  The tone  cannot be a r e l i a b l e r e c o g n i t i o n f a c t o r i n t h i s case, because the minute d e t a i l s are so great that there may object, e.g., a t r e e .  occur v a r i a t i o n s i n tone w i t h i n one  Neither can the shape of a tree be used e f f e c t i v e l y ,  because the i n t e r p r e t e r sees the arrangements of the branches rather than the whole shape i t s e l f .  In other words, the i n t e r p r e t e r i s too close  to the tree and therefore the enlarged branches of the tree hinder correct v i s i o n of the true crown shape. The a p p l i c a t i o n of these scales i s very l i m i t e d .  Generally  they are used only f o r study of very small d e t a i l s of an object f o r a special project. RF's varying between 1 : 7,000 and 1 : 9,000 provide  an  e x c e l l e n t working range f o r i d e n t i f i c a t i o n of Douglas f i r , western hemlock and western red cedar.  Since the minute d e t a i l s are reduced the combina-  t i o n of tone and texture can be applied with considerable  reliability.  Some minute d e t a i l s of a tree may be l o s t f o r i n t e n s i v e study, but the general arrangement of branches and d e n s i t y of the crown i s not influenced. The l o c a t i o n s of branches i n most cases are s t i l l c l e a r l y v i s i b l e .  The  shape of the crown i s a l s o b e t t e r v i s u a l i z e d and can be applied more e f f e c t i v e l y i n r e c o g n i t i o n of a t r e e , since the branches are reduced and the tree i s seen from greater distance than i n smaller scale photos (provided that both photos were made w i t h same f o c a l - l e n g t h camera).  The  impression of a form i s always b e t t e r from a distance than from a point too close to the object.  Good stereo r e l i e f representation and depth  perception of the trees are e a s i l y p o s s i b l e , the photographic p o s i t i o n as w e l l as slopes can be evaluated, and therefore the tree can be much  - 89 -  more e a s i l y studied i n r e l a t i o n to i t s environment than on smaller scale photos.  Information obtained from smaller scales i s more important i n  species determination  than the minute d e t a i l s obtained from large s c a l e s .  The area coverage per p r i n t i s a l s o greater (almost four times l e s s photo p r i n t s are needed f o r coverage of the same area), therefore the number of p r i n t s required f o r general area coverage i s not considered  excessive.  RF's varying between 1 : 14,000 and 1 : l 6 , 0 0 0 and beyond provide an e x c e l l e n t area coverage i n the broadest sense. physiographic  Major  d e t a i l s are e a s i l y seen, studied, and a l l o t t e d boundaries.  Land forms can be delineated only when great contrast i n pattern  occurs.  Slopes associated w i t h various land forms are not seen as e a s i l y as on 1 : 9,000 photos, and on very small scale photos, cannot be d i s t i n g u i s h e d at a l l .  The species i d e n t i f i c a t i o n on these photos i s very d i f f i c u l t or  cannot be resolved on photos showing no d i f f e r e n c e s i n r e c o g n i t i o n f a c t o r s of species.  Texture appears more or l e s s e q u a l l y f i n e f o r each species.  Shape of crown cannot be d i s t i n g u i s h e d because of excessive reduction i n size.  The only a p p l i c a b l e photo f a c t o r i s tone, which can be used only on  that scale of photos.  Mechanically they are easy to obtain; however, such  f a c t o r s as haze, crab and t i l t may become of great concern during the f l i g h t . 2.  Test of best photo scale i n species r e c o g n i t i o n The value of scale i n i d e n t i f i c a t i o n of species was tested  by an experiment.  Three scales of photographs were tested.  Photographs  w i t h large scale were 1 i n c h to 330 f e e t (RF 1 : 4,000); photos w i t h medium scale 1 i n c h to 730 f e e t (RF 1 : 8,700 ) and f i n a l l y photos w i t h small scales 1 i n c h to 1,500 f e e t (RF 1 : 16,000).  - 90 -  There were three i n t e r p r e t e r s .  I n t e r p r e t e r A with almost no  experience i n species i n t e r p r e t a t i o n , i n t e r p r e t e r B, s l i g h t l y more experience, and i n t e r p r e t e r C, had two years of experience i n the f i e l d of species i d e n t i f i c a t i o n . Ten Douglas f i r , ten western hemlock and ten western red cedar trees were examined.  Every tree was studied i n d i v i d u a l l y and  separately on each scale of photos which amounted to 90 steps to be identified.  Results of t h i s survey are shown i n Table 30, where the e r r o r s  are expressed numerically and i n percentages f o r each scale of photos, then summarized i n d i v i d u a l l y by i n t e r p r e t e r s . I t can be seen i n Table 30 that fewer e r r o r s were committed on the medium scale ( l : 8,000) p r i n t s , which was as expected, while more errors were made on the l a r g e r as w e l l as on the smaller scale photo p r i n t s . Most of the f a u l t s were committed i n separation of Douglas f i r and western hemlock.  This may be a t t r i b u t a b l e to the s i m i l a r appearance of these two  species on a e r i a l photos.  Fewer e r r o r s were made i n separation when these  two species were close together on the ground and the d i f f e r e n c e s i n appearance could be recognized more e a s i l y .  The l e a s t number of errors  was committed i n i d e n t i f i c a t i o n of western red cedar, which i s due to i t s e n t i r e l y d i f f e r e n t shape, texture and appearance i n comparison w i t h Douglas f i r and western hemlock. I t can be concluded from the table t h a t , w i t h experience, species i d e n t i f i c a t i o n may be improved considerably. S t e l l i n g w e r f (1961), also has c a r r i e d out a more or l e s s s i m i l a r experiment.  His examination involved the p h o t o - i n t e r p r e t a t i o n of  TABLE 30 Committed E r r o r s i n species r e c o g n i t i o n by d i f f e r e n t i n t e r p r e t e r s on various scales of photos. Inter- • Total preters No. of Trees to be identified A B C  No. of steps identif i e d correctly  90  in  90  kk Qk  90  E S c a l e LARGE N Species Wrc. Wh. Df. * 16  6  7  3  5  8  2  3  2  0  Le gend. N i  Number of errors -  Percentage of e r r o r s  53 15 5  r  r  o  r  o f p h o t o g r a p h s MEDIUM SMALL Species N Species Df. Wh. Wrc. Df. Wh. Wrc. k  6  2  50  5  5  k  16  1  1  1  Total No. of errors  Total No. of errors i n percentage  70  1+9  54  66  k6  51  26  16  18  s  12  ko 36  11 3  10  N 21  7  8  5  6  8  6  3  3  2  20 8  - 92 stands w i t h d i f f e r e n t a g e - c l a s s e s , and i d e n t i f i c a t i o n o f v a r i o u s t r e e s p e c i e s . H i s r e s u l t s are p r e s e n t e d T a b l e 31•  i n Tables  31  and  32.  Percentage correctness of p h o t o - i n t e r p r e t a t i o n f i g u r e s f o r species  Spruce  Douglas fir  Deciduous species  Total  under  30.6  48.3  15-1  31-3  right  44.2  40.5  45-3  43.5  over  25-2  11.2  39-6  25.2  100.0  100.0  100.0  100.0  Species estimated on photographs  Total  Table 32.  Percentage c o r r e c t n e s s o f p h o t o - i n t e r p r e t a t i o n f i g u r e f o r s p e c i e s i n d i f f e r e n t age c l a s s e s  Species estimated on photographs  Old aged  Middle aged  Young  Total  33-3 38.6  35-2  30.6  right  23.5 62.6  35-3  46.5  over  13.9  28.1  29.5  23.9  100.0  100.0  100.0  100.0  under  Total  - 93 -  THE VALUE OF HUMAN FACTORS IN PHOTO-INTERPRETATION  "The airphoto i s the window through which the viewer p r o j e c t s h i s background to determine what i s i n the view." (Frost, 1953)i n t e r p r e t a t i o n i s an a r t rather than a science.  Photo-  I t happens often that the  i n t e r p r e t e r knows what c h a r a c t e r i s t i c points he has to look f o r on the object to be i d e n t i f i e d , but he i s completely unable to v i s u a l i z e them. I t i s w e l l known that stereoscopic v i s i o n i s a basic requirement for photo-interpretation.  Moreover, there are a d d i t i o n a l other needs,  which are a t l e a s t as important to a photo-interpreter as stereo a c c u i t y . I f any\of these a b i l i t i e s i s missing, the i n t e r p r e t a t i o n w i l l not be complete, i n most cases. The human f a c t o r i n p h o t o - i n t e r p r e t a t i o n may be subdivided i n t o v i s u a l a c c u i t y and mental a c c u i t y ( C o l w e l l , 1954). (l)  Visual accuity When a p a i r of a e r i a l photographs i s looked a t through a  stereoscope, the instrument lenses take care o f the focusing f o r the eyeto-photo distance. converge.  I f the p r i n t s are oriented properly, the eyes do not  This v i s u a l p o s i t i o n i s the same, despite the nearness of the  photographs, as i f i t would be necessary to search f o r a small object a t a f a r distance.  In such cases the i n t e r p r e t e r works with such small d e t a i l s  d a i l y f o r long periods of time.  Therefore  the i n t e r p r e t e r ' s ocular  mechanism must be able to maintain v i s u a l e f f i c i e n c y through a whole work period.  - 9k Another requirement i s the a b i l i t y to perceive small d i f f e r e n c e s i n p a r a l l a x . This allows e x p l o i t a t i o n of the exaggerated stereo e f f e c t , which i s caused by long " a e r i a l eyebase".  (Actual ground distance between  p r i n c i p a l points of two consecutive photos). to a c e r t a i n l i m i t by experience.  This a b i l i t y can be increased  L o c a l conditions a f f e c t tree  i d e n t i f i c a t i o n very much on a e r i a l photographs.  An i n t e r p r e t e r working with  a photograph of a new l o c a l i t y may have l i t t l e d i f f i c u l t y i n separating various f o r e s t stand types.  He may have, however, great d i f f i c u l t i e s i n  determining the species, age classes and c o n d i t i o n o f the d i f f e r e n t i a t e d stands.  General r e c o g n i t i o n r u l e s and techniques of the photo i n t e r -  p r e t a t i o n provide the b a s i c information necessary, but the above-mentioned problem cannot be solved u n t i l the knowledge of i n t e r p r e t e r s i s supplemented by l o c a l f i e l d  reconnaissance.  The i n t e r p r e t e r ' s a b i l i t y t o i d e n t i f y objects on a e r i a l photographs i s r e l a t e d t o h i s f a m i l i a r i t y with the shape and dimensions of s i m i l a r or i d e n t i c a l objects.  The a b i l i t y t o i d e n t i f y an object w i l l be r e l a t e d t o the  number of times the i n t e r p r e t e r has seen and c o r r e c t l y i d e n t i f i e d s i m i l a r objects.  I f the i n t e r p r e t e r knows the v a r i a t i o n s i n appearance of an object  examined, i t enables him t o i d e n t i f y the object c o r r e c t l y .  Such knowledge i s  indispensable when i t i s necessary to determine tree species from a e r i a l photographs. On the b a s i s of what a photo-interpreter must do, i t can be s a i d that he should be able, a t l e a s t , t o : a.  See w e l l a t a distance,  b.  See w e l l close up,  - 95 -  (2)  c.  Maintain v i s u a l e f f i c i e n c y throughout the workday,  d.  See s t e r e o s c o p i c a l l y .  Mental a c c u i t y Besides good v i s u a l a b i l i t y , the i n t e r p r e t e r should have c e r t a i n  i n t e l l i g e n c e and p e r s o n a l i t y c h a r a c t e r i s t i c s . When photo-interpretation i s analyzed i n terms of v i s u a l requirements, i t may be seen that an i n d i v i d u a l can perform w e l l i n an i n t e r p r e t a t i o n t e s t , despite the f a c t that h i s ocular mechanism may be r e l a t i v e l y unsuitable  for photo-interpretation.  Conversely,  an i n d i v i d u a l who f a i l s such a t e s t might have eyes which are suited to the art.  I n the f i r s t case, the i n t e r p r e t e r has been mentally f i t , i . e . , he was  p a t i e n t , h i s imagination was good, and he was able to judge c o r r e c t l y despite the f a c t that h i s v i s u a l a b i l i t y was d e f e c t i v e .  I n the second case, despite  the i n t e r p r e t e r ' s good v i s u a l a b i l i t y , he was not able t o judge what he saw on photos.  Both defects might be improved with a strong w i l l and p a t i e n t  study. A very e s s e n t i a l requirement i s that an i n t e r p r e t e r have s u f f i c i e n t l o c a l experience i n the area to be examined.  The i n t e r p r e t e r  might have e x c e l l e n t v i s u a l a b i l i t y and might be mentally f i t , but i n the absence of l o c a l experience h i s r e s u l t s may e a s i l y turn out wrong. For e f f e c t i v e i n t e r p r e t a t i o n of tree species the i n t e r p r e t e r must have a good memory, i n t e r e s t i n h i s work, and must possess background i n f o r e s t r y , and r e l a t e d f i e l d s .  He must have a p a r t i c u l a r knowledge of the  e c o l o g i c a l r e l a t i o n s h i p s of the f o r e s t s i n the s p e c i f i c region with which he must deal.  I t i s necessary f o r him to know c h a r a c t e r i s t i c features of each  tree species, i n order t o d i f f e r e n t i a t e among them on photos.  He also has  - 96 -  to know how these c h a r a c t e r i s t i c s appear on d i f f e r e n t kinds of and i n d i f f e r e n t seasons of the year.  photographs,  In a d d i t i o n t o the above requirements  the i n t e r p r e t e r should be p h y s i c a l l y capable of p e r s i s t e n t study i n a leaning p o s i t i o n .  He should work w i t h good l i g h t i n g f a c i l i t i e s .  Glare  should be avoided. Stereoscopic a c c u i t y i s only one of the v i s u a l s k i l l s needed f o r photo-interpretation.  Other requirements include good distance v i s i o n ,  acceptable near v i s i o n , good reserves f o r accommodation and convergence, good ocular muscle balance and the v i s u a l capacity t o maintain an exacting search f o r small d e t a i l s .  The i n t e r p r e t e r should a l s o have p r o f e s s i o n a l  background, l o c a l experience and keep himself mentally f i t .  - 97 -  KEY TO AERIAL IDENTIFICATION OF DOUGLAS FIR, WESTERN HEMLOCK, AND WESTERN RED CEDAR  There are many types of keys which the i n t e r p r e t e r may use i n proceeding t o i d e n t i f y and analyze e i t h e r n a t u r a l or c u l t u r a l conditions i n an area.  The purpose of any key or s e r i e s of keys i s to point out or t o  c a l l a t t e n t i o n to objects or features of a pattern which w i l l guide i n c o l l e c t i n g data from an area examined. B a s i c a l l y there are two types of keys: (a) p o s i t i v e keys, and (b) inference keys (Simontacchi, 1955)-  P o s i t i v e keys permit d i r e c t  i d e n t i f i c a t i o n of o b j e c t s , c h i e f l y those w i t h which the reader i s already f a m i l i a r or those which lend themselves w e l l t o p i c t u r i n g and d e s c r i p t i o n . Keys based on inference are those r e q u i r i n g use of l o g i c , deductive reasons, and d e t a i l e d a n a l y s i s of r e g i o n a l and l o c a l environment.  Such a key  p i c t u r e s and describes s i t u a t i o n s , e i t h e r n a t u r a l or man-made, occurring i n one area assumed t o be t y p i c a l and then suggests, often by a s s o c i a t i o n , that analogous s i t u a t i o n s can e x i s t elsewhere, provided that n a t u r a l and environmental conditions are s i m i l a r .  The development as w e l l as the use  of such keys i s based on a n a l y t i c a l procedures. An inference key w i l l be presented f o r Douglas f i r , western hemlock, and western red cedar, grown i n the v i c i n i t y o f Vancouver and Haney.  The key i s most suited to large-scale photos and i s based p r i m a r i l y  on the tree's ground c h a r a c t e r i s t i c s , such as shape, branching h a b i t , l o c a l i t y , e t c . , as w e l l as on t h e i r p h o t o - c h a r a c t e r i s t i c s , such as tone  - 98 and texture.  I t i s , however, emphasized that the keys should be v e r i f i e d  and r e v i s e d by study of l o c a l f o r e s t regions. 1. (a)  Tone i s dark or medium dark and crowns are coniferous i n appearance  (b)  2  Tone i s medium or very l i g h t and crowns are coniferous 6  i n appearance 2. (a)  Trees are found i n mixed stands, where they may occur as dominant or codominant trees occupying 3.  rocky w e l l drained s i t e s 3. (a) Dominant trees have medium tone and u s u a l l y  k  pyramidal crowns (b)  Trees are u s u a l l y codominant, w i t h medium dark, or dark tone and have long pyramidal crown w i t h 5  drooping tops k.(a)  Trees grow w i t h sharp pointed crown on south dry-rocky, but w e l l drained middle and upper slopes.  The middle  and upper branches are tending upward, having long hanging side branches, g i v i n g uniformly coarse texture. The lower branches are s t r a i g h t (b)  Douglas  fir  Trees occur mostly on lower lands, tone i s medium dark, the branches are long and trending upward.  The  trunk i s c l e a r and the top i s l e s s pointed, and the crown u s u a l l y appears wider than i n h.(a).  Texture  i s coarse (c)  Trees have f l a t t e n e d or "broom l i k e " dead top. The trunk i s s t r a i g h t , w i t h i r r e g u l a r gaps between  Douglas  fir  - 99 branches. 5.(a)  T e x t u r e i s v e r y coarse  Douglas f i r  Trees have s h o r t and narrow c o n i c a l crowns. The b r a n c h e s a r e s l e n d e r and tend t o droop. top  twig leans gracefully.  causing a dark tone.  The  The f o l i a g e i s dense  T e x t u r e i s medium o r  " f e a t h e r y " , and t r e e s o c c u r u s u a l l y on a c i d soils (b)  Western hemlock  Tone i s d a r k , crown shape i s p y r a m i d a l .  The t o p  i s narrow, b u t s h o r t e r t h a n i n 5-(a), and the crown i s w i d e r . (c)  Texture i s coarser  Crown shape i s m o s t l y dome l i k e . l o n g , f l a t , o r p o i n t i n g downward.  Western hemlock  Branches a r e Long  i r r e g u l a r gaps o c c u r between w h o r l s and branches 6.(a)  Western hemlock  T r e e s have p o i n t e d narrow o r l e s s narrow c o n i c a l crown shapes, l i g h t o r v e r y l i g h t t o n e , and l a c y texture.  Branches a r e s l e n d e r and a l l curve upward.  Trees grow u s u a l l y on a c i d s o i l s , and u s u a l l y a r e e i t h e r dominant o r codominant (b)  Western r e d cedar  The crown i s s h o r t e r t h a n i n 5'(a), and l e s s narrow, but  s t i l l pointed.  The t o p i s more o r l e s s rounded  i f t r e e s are grown i n a dense s t a n d .  Tone i s  light (c)  Western r e d cedar  The crown i s l o n g and n o t u n i f o r m , w i t h a l o n g dead s p i k e l i k e t o p .  Long i r r e g u l a r c r o o k e d l i m b s  hang downward, b u t b r a n c h e s i n the upper p o r t i o n o f t h e crown may tend s l i g h t l y upward  Western r e d cedar  - 100 (d)  Tops are rounded, dome l i k e often with two or more leaders.  Tone i s very l i g h t , and texture i s f i n e r  than i n 6(c)  Western red cedar  - 101 -  CONCLUSION A e r i a l photographs have already proved t o have wide-spread a p p l i c a t i o n i n F o r e s t r y , and i t seems that they w i l l be put t o even greater use i n t h i s f i e l d i n the f u t u r e .  The needs of a f o r e s t - i n t e r p r e t e r d i f f e r  s i g n i f i c a n t l y from those other p h o t o - i n t e r p r e t e r s .  The f o r e s t e r must be  able not only t o measure and evaluate various timber stands, but a l s o t o d i s t i n g u i s h them, and t o recognize i n d i v i d u a l species.  He must be able t o  recognize t h e i r minute components, i . e . , i d e n t i f y species, whether they are growing i n the open or i n dense stands.  From the data and f a c t s presented  i n t h i s study the f o l l o w i n g conclusions can be drawn regarding the  process  of species i d e n t i f i c a t i o n : 1.  Components of a t r e e crown change w i t h t r e e age,  2.  Percentage of l i v e crown of Douglas f i r , western hemlock, and western r e d cedar t r e e s are c h i e f l y influenced by b a s a l area and height/crown width,  3-  The crown shape of Douglas f i r i s influenced by e l e v a t i o n ,  k.  Among the p i c t o r i a l q u a l i t i e s there are a few forms of information a v a i l a b l e f o r f o r e s t i n t e r p r e t e r s , among which the tone i s the most important, but t h i s should be used i n combination w i t h other factors.  5-  In the s e r i e s of photos studied, the smaller the scale the l i g h t e r was the tone,  6.  Among the many f a c t o r s i n f l u e n c i n g the texture of a t r e e image on a e r i a l photographs, the age and the scale are the most important.  - 102 7-  The best photo-scale  f o r the recognition, of Douglas f i r , western  hemlock^, and western red cedar has been found t o be about RF 1 : 8,700, 8.  Of the three f i l m s  used i n the i d e n t i f i c a t i o n of the tree species,  v i z . , panchromatic, i n f r a r e d , and colour f i l m s are used, i n f r a r e d p o t e n t i a l l y i s preferable, 9.  Colour f i l m s are l e a s t used, because of cost. f o r r e c o g n i t i o n of s p e c i a l problem  They are preferable  areas,such as caused by  c e r t a i n r u s t s and other tree diseases, 10.  The f i l m - f i l t e r - s c a l e combination i s a l o c a l problem and i s dependent on the nature of vegetation and the s p e c i f i c objectives desired,  11.  I t i s dangerous to generalize concerning the s p e c i f i c a t i o n of photography from one region to another. The w r i t e r of t h i s study hopes that some of the information  presented here w i l l prove to be of value i n the f u t u r e , y e t appreciates that much more research i n t h i s f i e l d i s required.  - 103 REFERENCES CONSULTED Aldred, A.H. 1959- I d e n t i f i c a t i o n of tree species on a e r i a l photographs. Thesis f o r the B.S.F. degree, F a c u l t y of F o r e s t r y , The U n i v e r s i t y of B r i t i s h Columbia, Vancouver, B.C. Andrews, G.S. 1934. A i r Survey and F o r e s t r y Developments i n Germany. For.Chon., 10:91-107. Andrews, G.S. 1940. Notes on the I n t e r p r e t a t i o n of V e r t i c a l A i r Photographs. For.Chon. l6:202-215Baker, F.S. 1950. P r i n c i p l e of S i l v i c u l t u r e . Toronto, Ont.  McGraw-Hill Book Co.,  Bauman, H. 1957- F o r s t l i c h e L u f t b i l d - I n t e r p r e t a t i o n . ( i n t e r p r e t a t i o n of Forest A e r i a l Photos). Selbsverlag der F o r s t d i r e c t i o n , Sudwurtemberg-Hohenzollern, Tubingen-Bebenhausen. Becking, R.W. 1959- F o r e s t r y A p p l i c a t i o n s of A e r i a l Color Photography. Photogram. Eng. 25(4):559-565. Benninghoff, W.S. 1950. Use of A e r i a l Photographs i n Mapping Vegetation and S u r f i c i a l Geology i n Subarctic Regions. Photogram. Eng., 16(4):428-429B i l l i n g s , W.D., and R. J . M o r r i s , 1951- R e f l e c t i o n of V i s i b l e and Infrared Radiation from Leaves of D i f f e r e n t E c o l o g i c a l Groups. Amer. Jour. Bot. 38:327-331. Bradshaw, K.E. 1950. Use of A e r i a l Photos by the Forest Survey i n C a l i f o r n i a . Photogram. Eng. l6(4):315-317Burks, G.F., and R.C. Wilson, 1939Vegetation Inventory from A e r i a l Photographs. Photogram. Engin. 5 ( l ) : 3 0 - 4 2 . A  Chapman, H.W.(l). 1949- Forest Reconnaissance by H e l i c o p t e r Empire Forestry. Rev. 28:340-342. Chapman, V.J.(2). 1949- The A p p l i c a t i o n of A e r i a l Photography to Ecology as Exemplified by the Natural Vegetation of Ceylon. Indian Forester. 73:287-314. Clark, W. 1947- Photography by I n f r a r e d . and Sons. New York.  Second E d i t i o n .  John Wiley  C o l w e l l , R.N. 1946. The Estimation of Ground Conditions from A e r i a l Photographic I n t e r p r e t a t i o n of Vegetation Types. Photogram. Eng. 12(2):151-l6l. C o l w e l l , R.N. 1948. A e r i a l Photographic I n t e r p r e t a t i o n of Vegetation f o r M i l i t a r y Purposes. Photogram. Engin. l4(4):472-481.  - 10k -  C o l w e l l , R.N. 1950-  New Techniques f o r I n t e r p r e t i n g A e r i a l C o l o r Photography.  J o u r . F o r . 48(3):204-205.  C o l w e l l , R.N. 1952. R e p o r t o f Commission V I I . ( P h o t o g r a p h i c I n t e r p r e t a t i o n ) t o t h e I n t e r n a t i o n a l S o c i e t y o f Photogrammetry. Photogram. Eng.  18(2):375-451.  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Photogram. Eng. 8(3):203-315'  - 108 -  A P P E N D I X  cl  -110-  APPENDIX I  4  5  6  Fig  2  V a r i a t i o n s in C r o w n  Shapes  of  Douglas  fir  Fig- 2 cont'd  V a r i a t i o n s in C r o w n  Shapes  of  Douglas  fir  2 cont'd  V a r i a t i o n s in C r o w n  k  Shapes  of  Douglas  fir  I  Fig-  3  V a r i a t i o n s in C r o w n  c  Shapes  of  Western  hemlock  d  80  3 D  Graph I  50  70  90  Age in Years  Average top angles over age for Douglas fir  MO  130  Age in Years Graph 3  Average top angles over age for Western red c e d a r  A  Sensitivity  curve  of orthochromatic  film  CO  c  a>  co  4XlO"  5  cms-  5  B  Sensitivity  Wave Length (cm)  6  7  curve of panchromatic  film  CO  c CO CO  4xl0"  cms  5  C  5  Wave Length (cm)  6  Sensitivity curve of i n f r a - r e d  film  CO  c  a>  co  4xlO~  Fig- 7  5  cms  5>6  Wave Length (cm)  7  Sensitivity curves of various types of film  8  

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